The Edge trems are generally regarded as Ibanez's best. The TRS trems were on cheaper models and can be a real pain to keep in tune (although some would argue that they're fine). Ibanez recently released the Edge 2, which is said to be as good as the Edge (I haven't played one) and an interesting one they call 'ZR' or 'Zero Resistance' which are supposed to be very nice. Again, I haven't played one, but from what I an see they seem to be like a Wilkinson without the locking.
Check out Jemsite, especially the forums, for lots of info on Ibanez guitars.
I must say that the Edge on my 540S is the best FR-like bridge I've ever played. Dead on tune every time.