Here is my opinion,

Triton and Roland XP series are good for synth sounds and not for acoustic emulation. I would go with Roland XV-series or Motif. The new motif ES promises to be spectacular. It seems to me that Yamaha experiments with top arrangers and then brings the voices to motif:

PSR9000PRO-> Motif
TYROS-> Motif ES.

Although it seems to me that Motif ES cotains a very large library of sounds. Yamaha claims it to be the largest library ever.