I love my Pioneer Elite receiver. Personally, I wouldn't get one unless it was one of the Elite models. I have the cheapest of the Elites. When I bought it, it was $700 and I got it for $630 with 10% off. The last I checked, on-line, it was MSRP $800, but perhaps it's gone back down since then. I'm only driving 8 ohm speakers, but, so far, I haven't heard anything negative about the Elites not being able to drive the 4 ohm loads. It has plenty of power to drive what I currently have.
MCCACC is simple to use and seup with a single microphone position. You also can save up to 6 seperate settings with the one I have. The cheaper ones have less.
If I ever buy another one, I might get a Denon just so I can experience the difference. I think the Denon may be superior to the Onkyo, but I don't have anything to back that up really, so I really don't know. Just that I've heard a lot of good things about Denon.
Personally, after functionality, I would probably base my decision on weight, because I think that with added weight comes superior power supply, which to me equates to better sound.