Given the list as-is I'm not sure how to vote. Adcom and Outlaw can be cut quickly. Adcom because they're nothing special, and Outlaw because they're just repackaged ATI stuff, albeit at lower prices. ATI amps are very nice, at least performance-wise, but the best? Hmmm. Classe is now made in China yet still sold at silly prices, since B&W bought them. McIntosh is off the list IMO because those gimmicky output transformers mar otherwise high-quality, robust designs. It's time to move on, McIntosh. I've never thought Bryston was worth the prices they charge, though they're nice stuff. Krell is an interesting case, but I wouldn't buy them because I'm still pissed at them for forcing the founders out. Dumb. The new Krell designs since Dan left are an unknown. I'm with Gene on the Pass Labs issues, and balanced single-ended design does seem a little gimmicky too. Different just to be different? Boulder? They probably are "the best" on this list, build-quality-wise. The Emotiva amps are a bargain, but my experience with their CD player makes me wonder too much about build quality. The basic amps are probably the only products of theirs I'd take a chance on.
If I were buying now I'd probably choose ATI again, just for lack of a more compelling plan. The budget (ha!) Boulder 860 at $8500 looks like a work of art and measures well, but it really doesn't tempt me. The amplifier market has gotten a lot more boring over the years. A big contrast to the subwoofer market, which has gotten incredibly interesting in the past couple of years.