I'd agree about the Mercury II. As an added feature, it has excellent access to functions to delete, rename and organize the channels you find. Very important so you can clean up after a scan and give them names that make sense.
Because other features vary so much, I'd just give you a list that are currently in production, and suggest you get feedback on these models.
That'll cut down your research to a manageable amount.
Traxis 3500 - seems fast and well liked
FortecStar Mercury II - well supported, quite popular
Pansat 3500sd - will control co-rotor if that's helpful, has SD card for updates
Visionsat IV-200 - USB update, and PVR with external USB drive
Lots of readers above have commented favorably on most of 'em.
But, if anyone wants to bash any of these, go right ahead.
At least these are pretty well known by the members.
. . . and none are the hacker-bait junk receivers sold by many.
Pansat 3500 sd, i.e. the one with the sd card reader rocks. I love mine. Only thing is it doesn't do the new dvb s2 signals that equity will start pumping out in the near future, so if you are wanting it for 123w, you might be out of luck. Most other stuff, at least on the KU side, works fine. I can't speak about the C band since I don't have a 6' or 6' + dish... The sd card does make things nice for channel editing purposes if you use channel master... Be aware though, it's highly possible to get tp overload with this receiver if you scan every bird in the sky including all the echostars looking for fta signals and don't go back and delete out as many tps as you can afterwards. It's not really much of an issue in regular everyday use, just something to be aware of for the first month or so you own the thing. Kinda freaked me out when it first happened... you get it doing oddball things like changing disecq numbers to 4000 or something when you only have 4 ports, etc. and changing channel names and frequencies to really weird names and numbers. A simple factory reset helps fix all of that though... as does saving your channel bin to the sd card often so that you have it as a backup in case something odd like that happens. You don't have to have each tp loaded once you scan in the channels.... so deleting non-used tps doesn't hurt anything, it just frees up more flash memory on the machine to allow for future tps to be scanned in either with the blind scan or manual entry. One word of caution though... I think factory resets or software saves to the sd card that you use to do something similar to factory reset may offset your true diseqc positioning just a little since it might erase your settings a little. Nothing that a simple move a few degrees east or west when looking at signal strength doesn't help fix. No matter what you get, make sure to use one of those surge protector things that have the coax surge protector built in and have that coax protection going to the line going from the satellite dish to the receiver.