Kurzweil - I personally have a PC2 (the PC1SE does not have the KB3 Hammond emulator, but has all the other sounds, including the Orchestral and Vintage sounds.
The Kurzweil TripleStrike Piano is a very very good electronic emulation of a concert grand piano. The Rhodes and Wurly sounds - especially the ones in the Vintage ROM that is included are excellent. String sounds are good, and you have your choice of generic string sounds or orchestral string solo and sectionals, also including some string effects for use in layering.
The only thing better is the new Kurzweil PC3X, which will be out this month (and mine is alreay on order) It has a whole ROM of String sounds that have never been released before, AND newer higher resolution samples of the PC2 and PC1 sounds.
Note that this is my opinion - I personally do not like the pianos on Korg, Yamaha, or Roland. I want something that sounds like a real acoustic instrument - not an electronic copy. I personally have a K2000VP synth (15 years old), SP88X stage piano, PC2, and K2661 synth already from Kurzweil. I do not work for the company or in any way have special pricing.
Before spending your money LISTEN to them all. Preferably, carry a first-class set of headphones (like Sennheiser or some of the high end Sony), plug in and listen - then make up your mind which sounds you like best.
Jim