Nice write up here!
A couple of years ago, Onkyo really brought it to the competition, bringing features and quality to lower price points than just about anybody else at the time.
Denon has stayed very consistent. They're usually not the cheapest, but their power section is as rock solid as ever and they are always competitive in terms of features.
H/K too seems to be very consistent, but, unfortunately, consistent in offering fewer features at any given price bracket. Their power section is rock solid though.
Yamaha has been disappointing me over the past couple of years. They've let their power section decrease in quality in order to keep up with features and lower price points.
Pioneer seems to really be on the rise at the moment. They remind me a lot of Onkyo from a couple of years ago as they are pushing the envelope in terms of features whilst keeping their power section decent and lowering prices.
I remain a Denon fan - they are just "safe" as you can almost always rely upon them to be up-to-the-minute in features and rock solid in amplifier performance. Pioneer are the exciting ones at the moment though, but I fully expect that Yamaha will do a whole-hog revamp of their design within the next couple of years in order to pull the same sort of leap-frog over everyone. Onkyo, Pioneer and Yamaha seem to do that on about a 6 year cycle, so it's always fun to watch them battle it out