Onkyo (since I just ordered one).
I've actually never owned anything from Onkyo before, so it will be a test drive of sorts. For whatever reason, I don't feel much brand loyalty when it comes to receivers. Every mass-market brand seems to be ready to whore themselves out to the latest licensed (or equivalent in-house) technology instead of doing a better job at the basics. Marketing drives product development.
On the other hand, I could've voted with my dollars for another approach by going with a boutique brand that emphasizes the basics, so I guess I'm just as at fault. Don't say I'm not cynical, though.
Other brands I have owned are Pioneer and Sherwood. I don't get the same itch to upgrade receivers that I do for other gear...just now doing it for the convenience of HDMI and a powered 2nd zone in what will be my most permanent home theater yet. Had those features not been a factor, I think I would've been fine with my 10+ year old Pioneer for several more years.
I have yet to experience a jump in home theater sound quality (independent of speakers) equivalent to the switch from Pro Logic to AC3/DTS. Lossless codecs and 7+ speakers don't do much for me, I'm afraid.