I had ExpressVu for about a year and decided to get Star Choice. I have had both running for about 2 weeks now, so I decided to do a comparison of the two. All opinions are mine, but you should get the general idea. (All prices listed are in Canadian dollars). This is a little long 
Installation:
ExpressVu uses the same equipment as Dish Network, so the install is a little easier if you have done a Dish Net or DirecTv install before.. It comes with a 20" dish, Y adapter and one LNB. This poses a problem, as new channels, HD channels and ethnic (ethnic..not French) channels are being put on the Nimiq 2 satellite. So if you want these channels, you need to upgrade equipment right away. If you purchase a HD receiver (6100, which is the brother of Dish Network 811), you do receive both LNB's and a SW21. You can use a Twin in place of the 2 duals and eliminates the switches. I had an extra SW21 and a dual LNB laying around, so I was set to receive both satellites. One other thing to note is ExpressVu split some of the channels off of Nimiq 1 and put them on their "new" satellite, Nimiq 3. Nimiq 3 is an old Directv satellite and didn't cover all of Canada, so they moved it north to cover Canada. This eliminated the coverage in the Southern US and the West coast. So if you're in Oregon, California, Arizona, New Mexico, etc. you won't have access to about 8 transponders (even with a larger dish).
Star Choice uses a quad LNB that comes standard with a new kit, which allows you to see both satellites and can hook up to 4 receivers without any additional equipment (except for a receiver of course). Since Star Choice uses a lower powered satellite (KU Band), the dish is larger. The standard dish is a 60e, which is like a 24" dish. Since the footprint is weaker in the US, I went with a 75e, which is 37" x 27", and is like a 30" dish.
Installation of the ExpressVu took about 10 minutes once I had elevation and skew set. I was able to obtain a 75-80 on most transponders for 91 (Nimiq 1). However, Nimiq 2 was around 70 for most transponders. The Star Choice system takes a little more patience, as with any KU install, you cant slowly move it where you think it it should be. You have to get where azimuth is, move it 1/4 inch or less, and wait 5 seconds. I got skew and elevation to the numbers that they should be and aimed where I thought it would be. Since the satellite you need to aim at is at 111.1, if you've installed a Dish Network system, it is close to it. To aim, you don't go into the system signal screen, you go into the diagnostic C screen. There is a number in there that is either a plus (+) or minus (-). When the signal is detected, this number moves every second, and will be greater than +7.5. Within 5 minutes, I was able to get a 9.4 to 9.6 on the screen. Most channels on the main satellite (107.3) are between 9.5 and 10 and between 12 and 12.5 on the new satellite (111) . The signal quality on most channels is between 87-99 (max of 100).
Advantage......Star Choice. Even though you need a little more patience to install, the fact that no extra equipment is needed up front and you can hook up 4 receivers right away more than makes up for the dish size.
Receivers:
ExpressVu uses Dish Network equipment, so if you've used Dish you will be real familiar with it. StarChoice uses equipment by Motorola. Both have an entry level unit (SC205 and Evu 3100) and a HD receiver (SC500 and Evu 6100). Star Choice has a receiver (315) that has a Dolby digital output. ExpressVu has a PVR (5900) and recently started selling dual tuner units. The 3200 and 5200, which are clones of Dish Networks 322 & 522. These units are new so I can't comment on the bugs/features of the units. The guide on StarChoice is a little slower, but is colorized for Sports, movies, news and other programs and can go out for approximately 3 days. ExpressVu has a search function, but is a plain gray and can go up to 46 hours. Also, if you leave the unit on and not put the unit in standby, the guide will not update. The Star Choice guide will update regardless if the unit is on or not. The Star Choice receivers are smaller in size and are less expensive. Star Choice has no contract, ExpressVu has a 1 or 2 year contract. For users in the US, a 1 yr is needed. You have the option of having more than one receiver, but for ExpressVu, I highly suggest NOT having more than one, due to the fact that ExpressVu requires you to plug all receivers into the phone line. Since you can't plug it into the phone line if you live in the US, if you have more than one receiver ExpressVu might call to verify that all receivers are in the same house. This doesn't work if you are in the US. Star Choice doesn't do this, so a second receiver can be done with Star Choice. Heck, the 205 receiver doesn't have a spot for a phone line. If you add a receiver, it's 4.99 for the extra receiver
Advantage.....ExpressVu due to the option of PVR or dual tuner units. However, with the bugs these units have, if I wanted a PVR I'd get the 5900.
Programming:
Programming is about the same. Both have an "Essentials pack", that is required for all packages. This includes Canadian Networks (CTV, CBC, Global) from across Canada, Independent stations (CH, New Nets), Educational (Access, SCN), Weather, and a set of US Networks. (ABC, CBS, NBC, FOX, PBS)
ExpressVu's options are Seattle and Boston. Depending on your address, the Nets are per address (Manitoba East gets Boston, Alberta West gets Seattle). You can add the other set of Networks for $1.
Star Choice has more options. They have Detroit & Buffalo in the East and Seattle & Spokane in the West. You can select any one of the 4 cities. The Fox Network from the East always was from Rochester, NY and only recently did Detroit Fox become available. You can add one city from the other direction for 6.99 alacarte or a theme.
ExpressVu does have in its Essentials YTV and Treehouse TV, which are like Nickelodeon. StarChoice does have TSN (The Sports Network, think ESPN) in its Essentials pack.
Since most of the CTV, CBC and Global are owned by the Network, you have 5 chances to see a program due to time shifting. So if you miss your favorite program that is on at 8 and live in MN, you can see it at 9, 10, and 11. Conversely, if you live in Seattle, you can see your programs 4 hours earlier. You can see Letterman or Leno at 8:30 if you live in Seattle. There are also "local" locals, which are CBC & CTV that are not owned by the network. These are in places like Thunder Bay, Kenora, Lloydminster, Dawson Creek, and Prince George. If you have ExpressVu, unless you live in one of these areas, you will not be able to see these. Star Choice, on the other hand, opens these channels up for everyone. You might think "Why would I need 5 more CBC's or CTV's?" Well, since some of these locals are the only option in the city they serve, they mix programming (as an example, some CTV programming is on CBC Thunder Bay because some Global programming is on CTV Thunder Bay) they have to stagger programming. So programming may be on a day earlier, or earlier in the day than what everyone else could see. This, along with Time Shifting, makes both a great option.
Advantage....Star Choice for 2 reasons. Since I'm a sports fan, having TSN in the basic package is great. Also, the "local" locals make it good to see programming later in the week. Some shows are shown a day or two later on the TV stations in Kenora & Lloydminster so if I miss my program on Monday, I should be able to see it Tuesday night. ExpressVu does allow you to add a second set of US Nets for $1 (vs. 6.99). However, since most of the programs on US Nets are shown on CTV or Global, it's a moot point.
Themes:
The major advantage of Canadian satellite is you don't have to get a huge package with channels you don't want like Directv or Dish Network. So if you're a Sports fan, you don't need kids programs. If you could care less about sports, you don't need Sports themes. Themes are $6.99 with Star Choice & $5 for ExpressVu. If you purchase more than a couple themes, you can save some money with packages. StarChoice has a package with 3 themes and the Essentials for 37.99. ExpressVu has a package with 5 themes and Essentials for $45. You can purchase some channels on both systems alacarte. So you don't even need to get a full theme if you don't want. Star Choice has channels for 1.99 each (some are .99 and 2.99, but most are 1.99). ExpressVu has channels for 2.50 a piece, but when compared to $5 for a theme, really isn't a good deal in my mind. ExpressVu does have some channels that Star Choice doesn't. Some of these are Drive in Classics, Much Loud, Much More Retro, BPM, Much Vibe, and a couple more. Some of the channels that are packaged with Themes make you wonder. As an example, with Star Choice, Spike TV is in Music and on ExpressVu WGN is packaged with Sports.
Advantage: ExpressVu just on the basis of more options for channels. If ExpressVu would let me have just the theme with Much More Retro & Much Loud, I'd keep it
Audio channels:
Both systems have audio only channels and some radio stations from across Canada. ExpressVu has 45 audio only from Galaxie StarChoice has 40 channels, which are a mix of channels from Galaxie & Max Trax.ExpressVu has 30 radio stations from across Canada, with stations such as the CBC Radio One and Two, French CBC (SRC), and stations from Calgary, Toronto and my personal favorite, Power 97 in Winnipeg. The only problem with these is the radio stations are spread amongst 2 or 3 themes. Star Choice has 6 or 7 stations from Spokane, WA in its basic package. You can add 45 radio stations from across Canada for 2.99 a month (or included in the Music theme).
Advantage: Star Choice..ExpressVu only has about 10-12 commercial radio stations to choose from. Star Choice has around 25 from various locations such has Vancouver, Calgary, Edmonton, Toronto, Montreal, and from small towns such as Whitehorse.
High Definition
I don't have HD so I can't do much of a comparison. I do know Star Choice includes 9 HD channels in the Essentials. The main problem is the HD is real sporatic, and you don't know what programs are on what channel. ExpressVu has around 25 HD channels, such as WGN HD, TSN HD, Sportsnet HD, Discovery HD, and both sets of US Nets in HD.
Picture and sound:
ExpressVu has more channels..that's good. However, ExpressVu puts most of the channels on Nimiq 1 (the main satellite) and only recently has put channels on Nimiq 2 so they compensate by cramming up to 12 channels per transponder..that's bad. Result: Some channels look real bad. They only have one uplink to the subscribers, and that is from Toronto. So if there is a big storm in Toronto, your signal may show 100%, but you may have no picture or pixelated. StarChoice had a different idea. Put the English channels on F1 (main) and the French on F2 (new). This makes compression not as bad (there is only 7-8 channels on a Transponder). The picture is much clearer on most channels on Star Choice. A couple CBC & CTV channels are picked up over the air, so it is quite interesting to see ghosting on a satellite picture. Star Choice uses multiple uplink facilities, so your odds of having an outage due to the uplink are much less. ExpressVu has a problem with audio output on their channels. Some are way too low, where some are much louder. So if you are on TSN, which is low and go to CBC Ottawa, you get blown out of your chair. Most channels are too low in my mind compared to my Dish Network system and over the air. Star Choice has most channels the same volume....loud (which is good). I'd rather have to turn the TV down when watching Star Choice versus having to crank it up. ExpressVu's picture on some channels is real dark. Star Choice is a little brighter and most channels look the same.
Advantage: Star Choice...due to sound volume being level across the channels and picture being much clearer (again, my opinion).
So there you have it. A comparison between Star Choice and ExpressVu. Personally, I like Star Choice due to louder (and more level) sound, smaller receivers, and the "local" locals are available. (Now if SC would get Much More Retro, I'd be even happier)

Installation:
ExpressVu uses the same equipment as Dish Network, so the install is a little easier if you have done a Dish Net or DirecTv install before.. It comes with a 20" dish, Y adapter and one LNB. This poses a problem, as new channels, HD channels and ethnic (ethnic..not French) channels are being put on the Nimiq 2 satellite. So if you want these channels, you need to upgrade equipment right away. If you purchase a HD receiver (6100, which is the brother of Dish Network 811), you do receive both LNB's and a SW21. You can use a Twin in place of the 2 duals and eliminates the switches. I had an extra SW21 and a dual LNB laying around, so I was set to receive both satellites. One other thing to note is ExpressVu split some of the channels off of Nimiq 1 and put them on their "new" satellite, Nimiq 3. Nimiq 3 is an old Directv satellite and didn't cover all of Canada, so they moved it north to cover Canada. This eliminated the coverage in the Southern US and the West coast. So if you're in Oregon, California, Arizona, New Mexico, etc. you won't have access to about 8 transponders (even with a larger dish).
Star Choice uses a quad LNB that comes standard with a new kit, which allows you to see both satellites and can hook up to 4 receivers without any additional equipment (except for a receiver of course). Since Star Choice uses a lower powered satellite (KU Band), the dish is larger. The standard dish is a 60e, which is like a 24" dish. Since the footprint is weaker in the US, I went with a 75e, which is 37" x 27", and is like a 30" dish.
Installation of the ExpressVu took about 10 minutes once I had elevation and skew set. I was able to obtain a 75-80 on most transponders for 91 (Nimiq 1). However, Nimiq 2 was around 70 for most transponders. The Star Choice system takes a little more patience, as with any KU install, you cant slowly move it where you think it it should be. You have to get where azimuth is, move it 1/4 inch or less, and wait 5 seconds. I got skew and elevation to the numbers that they should be and aimed where I thought it would be. Since the satellite you need to aim at is at 111.1, if you've installed a Dish Network system, it is close to it. To aim, you don't go into the system signal screen, you go into the diagnostic C screen. There is a number in there that is either a plus (+) or minus (-). When the signal is detected, this number moves every second, and will be greater than +7.5. Within 5 minutes, I was able to get a 9.4 to 9.6 on the screen. Most channels on the main satellite (107.3) are between 9.5 and 10 and between 12 and 12.5 on the new satellite (111) . The signal quality on most channels is between 87-99 (max of 100).
Advantage......Star Choice. Even though you need a little more patience to install, the fact that no extra equipment is needed up front and you can hook up 4 receivers right away more than makes up for the dish size.
Receivers:
ExpressVu uses Dish Network equipment, so if you've used Dish you will be real familiar with it. StarChoice uses equipment by Motorola. Both have an entry level unit (SC205 and Evu 3100) and a HD receiver (SC500 and Evu 6100). Star Choice has a receiver (315) that has a Dolby digital output. ExpressVu has a PVR (5900) and recently started selling dual tuner units. The 3200 and 5200, which are clones of Dish Networks 322 & 522. These units are new so I can't comment on the bugs/features of the units. The guide on StarChoice is a little slower, but is colorized for Sports, movies, news and other programs and can go out for approximately 3 days. ExpressVu has a search function, but is a plain gray and can go up to 46 hours. Also, if you leave the unit on and not put the unit in standby, the guide will not update. The Star Choice guide will update regardless if the unit is on or not. The Star Choice receivers are smaller in size and are less expensive. Star Choice has no contract, ExpressVu has a 1 or 2 year contract. For users in the US, a 1 yr is needed. You have the option of having more than one receiver, but for ExpressVu, I highly suggest NOT having more than one, due to the fact that ExpressVu requires you to plug all receivers into the phone line. Since you can't plug it into the phone line if you live in the US, if you have more than one receiver ExpressVu might call to verify that all receivers are in the same house. This doesn't work if you are in the US. Star Choice doesn't do this, so a second receiver can be done with Star Choice. Heck, the 205 receiver doesn't have a spot for a phone line. If you add a receiver, it's 4.99 for the extra receiver
Advantage.....ExpressVu due to the option of PVR or dual tuner units. However, with the bugs these units have, if I wanted a PVR I'd get the 5900.
Programming:
Programming is about the same. Both have an "Essentials pack", that is required for all packages. This includes Canadian Networks (CTV, CBC, Global) from across Canada, Independent stations (CH, New Nets), Educational (Access, SCN), Weather, and a set of US Networks. (ABC, CBS, NBC, FOX, PBS)
ExpressVu's options are Seattle and Boston. Depending on your address, the Nets are per address (Manitoba East gets Boston, Alberta West gets Seattle). You can add the other set of Networks for $1.
Star Choice has more options. They have Detroit & Buffalo in the East and Seattle & Spokane in the West. You can select any one of the 4 cities. The Fox Network from the East always was from Rochester, NY and only recently did Detroit Fox become available. You can add one city from the other direction for 6.99 alacarte or a theme.
ExpressVu does have in its Essentials YTV and Treehouse TV, which are like Nickelodeon. StarChoice does have TSN (The Sports Network, think ESPN) in its Essentials pack.
Since most of the CTV, CBC and Global are owned by the Network, you have 5 chances to see a program due to time shifting. So if you miss your favorite program that is on at 8 and live in MN, you can see it at 9, 10, and 11. Conversely, if you live in Seattle, you can see your programs 4 hours earlier. You can see Letterman or Leno at 8:30 if you live in Seattle. There are also "local" locals, which are CBC & CTV that are not owned by the network. These are in places like Thunder Bay, Kenora, Lloydminster, Dawson Creek, and Prince George. If you have ExpressVu, unless you live in one of these areas, you will not be able to see these. Star Choice, on the other hand, opens these channels up for everyone. You might think "Why would I need 5 more CBC's or CTV's?" Well, since some of these locals are the only option in the city they serve, they mix programming (as an example, some CTV programming is on CBC Thunder Bay because some Global programming is on CTV Thunder Bay) they have to stagger programming. So programming may be on a day earlier, or earlier in the day than what everyone else could see. This, along with Time Shifting, makes both a great option.
Advantage....Star Choice for 2 reasons. Since I'm a sports fan, having TSN in the basic package is great. Also, the "local" locals make it good to see programming later in the week. Some shows are shown a day or two later on the TV stations in Kenora & Lloydminster so if I miss my program on Monday, I should be able to see it Tuesday night. ExpressVu does allow you to add a second set of US Nets for $1 (vs. 6.99). However, since most of the programs on US Nets are shown on CTV or Global, it's a moot point.
Themes:
The major advantage of Canadian satellite is you don't have to get a huge package with channels you don't want like Directv or Dish Network. So if you're a Sports fan, you don't need kids programs. If you could care less about sports, you don't need Sports themes. Themes are $6.99 with Star Choice & $5 for ExpressVu. If you purchase more than a couple themes, you can save some money with packages. StarChoice has a package with 3 themes and the Essentials for 37.99. ExpressVu has a package with 5 themes and Essentials for $45. You can purchase some channels on both systems alacarte. So you don't even need to get a full theme if you don't want. Star Choice has channels for 1.99 each (some are .99 and 2.99, but most are 1.99). ExpressVu has channels for 2.50 a piece, but when compared to $5 for a theme, really isn't a good deal in my mind. ExpressVu does have some channels that Star Choice doesn't. Some of these are Drive in Classics, Much Loud, Much More Retro, BPM, Much Vibe, and a couple more. Some of the channels that are packaged with Themes make you wonder. As an example, with Star Choice, Spike TV is in Music and on ExpressVu WGN is packaged with Sports.
Advantage: ExpressVu just on the basis of more options for channels. If ExpressVu would let me have just the theme with Much More Retro & Much Loud, I'd keep it

Audio channels:
Both systems have audio only channels and some radio stations from across Canada. ExpressVu has 45 audio only from Galaxie StarChoice has 40 channels, which are a mix of channels from Galaxie & Max Trax.ExpressVu has 30 radio stations from across Canada, with stations such as the CBC Radio One and Two, French CBC (SRC), and stations from Calgary, Toronto and my personal favorite, Power 97 in Winnipeg. The only problem with these is the radio stations are spread amongst 2 or 3 themes. Star Choice has 6 or 7 stations from Spokane, WA in its basic package. You can add 45 radio stations from across Canada for 2.99 a month (or included in the Music theme).
Advantage: Star Choice..ExpressVu only has about 10-12 commercial radio stations to choose from. Star Choice has around 25 from various locations such has Vancouver, Calgary, Edmonton, Toronto, Montreal, and from small towns such as Whitehorse.
High Definition
I don't have HD so I can't do much of a comparison. I do know Star Choice includes 9 HD channels in the Essentials. The main problem is the HD is real sporatic, and you don't know what programs are on what channel. ExpressVu has around 25 HD channels, such as WGN HD, TSN HD, Sportsnet HD, Discovery HD, and both sets of US Nets in HD.
Picture and sound:
ExpressVu has more channels..that's good. However, ExpressVu puts most of the channels on Nimiq 1 (the main satellite) and only recently has put channels on Nimiq 2 so they compensate by cramming up to 12 channels per transponder..that's bad. Result: Some channels look real bad. They only have one uplink to the subscribers, and that is from Toronto. So if there is a big storm in Toronto, your signal may show 100%, but you may have no picture or pixelated. StarChoice had a different idea. Put the English channels on F1 (main) and the French on F2 (new). This makes compression not as bad (there is only 7-8 channels on a Transponder). The picture is much clearer on most channels on Star Choice. A couple CBC & CTV channels are picked up over the air, so it is quite interesting to see ghosting on a satellite picture. Star Choice uses multiple uplink facilities, so your odds of having an outage due to the uplink are much less. ExpressVu has a problem with audio output on their channels. Some are way too low, where some are much louder. So if you are on TSN, which is low and go to CBC Ottawa, you get blown out of your chair. Most channels are too low in my mind compared to my Dish Network system and over the air. Star Choice has most channels the same volume....loud (which is good). I'd rather have to turn the TV down when watching Star Choice versus having to crank it up. ExpressVu's picture on some channels is real dark. Star Choice is a little brighter and most channels look the same.
Advantage: Star Choice...due to sound volume being level across the channels and picture being much clearer (again, my opinion).
So there you have it. A comparison between Star Choice and ExpressVu. Personally, I like Star Choice due to louder (and more level) sound, smaller receivers, and the "local" locals are available. (Now if SC would get Much More Retro, I'd be even happier)