There is no one HD receiver that does it all, and there is no receiver that doesn't have bugs, so which is best kind of depends on a tradeoff between what you want to watch and the bugs in the receiver that get's those things.
I have an Azbox elite, Diamond 9000, and Coolsat 8100 STBs, and add to that several PC based receivers like the Twinhan 1020a, TT3200, Broadlogic 1030, and Genpix Skywalker 1, all of which give me HD capability, however to watch HD via the PC receivers, I need to stream to either the Azbox, a ROKU HD1000, or PopCornHour.
Of the STBs, despite the fact that they have yet to come out with anything but beta software for the receiver, and people have been complaining about the receiver's bugs right and left, it is my favorite receiver, mainly because it is the easiest to manually program in DVB-S2 transponders, and it does 4.2.2 HD. The Azbox does have some limitations, primarily that it can't record or play streams of high bitrate HD. I have hopes that someday this will be fixed, but have been waiting over a year, and no fix yet, so it may never come. If it could play high bitrate streams, that would be great, because it would replace both my Roku and PopcornHour.
The Azbox Elite doesn't have blind scan, but people have been reporting all sorts of bugs with the newer models that do have blind scan. I really believe that 90% of the problems people report are due to the way people are using their receivers, as some people don't seem to have any problems, however it's hard to recommend one of those receivers until the source of the problems is determined.
Anyway, to me, 4.2.2 is important, so Azbox is the only answer, other than getting a much faster computer. If you're not interested in 4.2.2, then one of the other STBs, like Pansat or one of the newer STBs might be a better choice. Personally, I do 90% of my actual sat viewing by streaming from my PC cards, mainly because I tend to record things for later viewing, or delay live viewing, neither of which I can do with an STB until Azbox fixes their bitrate limit.
Anyway, Azbox is the most capable receiver out there, but be prepared for confusing behavior or bugs.