Yamaha. I wouldn't spend my money on any other power amp - or yours, either, unless you insisted.
Come to think of it, I actually made the jump from lurker to member about 8 years ago just because I couldn't let another power amp thread go by in silence, and what I said then (and more than once since, IIRC) holds true now:
As a former full-time soundman, I used Crown, Crest, QSC, BGW, Peavy, Traynor, and probably a few that have slipped my mind. Every amp I used by every one of the above brands quit mid-gig more than once.
There is also one brand that has always taken what I put in and given it back to me loud - no color, no distortion; that happens to also be the one brand that has never broken down on me - or anyone I know - and that is Yamaha.
Best sound* + best reliablity = no brainer.
*I will stipulate that my thoughts on the matter are formed from a SR point of view, and that some may prefer the color that one or another of the lesser amps adds to the sound for instrument rig use. But they'll still let you down.
IME, reliability goes:
1. Yamaha
(big gap)
2. BGW
(little gap)
3. QSC
4. Crest
5. Crown
6. Any I may have forgotten
(bigger gap)
7. Traynor
8. Peavy
Sound goes about the same.
Peter