The only keyboard player I've noticed and appreciated is the big beardy guy in The Band (Garth Hudson?). Don't really listen to synth-type music.
For rock players, I'd go with the following list:
1) I vote for Garth number one..
2) Nicky Hopkins (John Lennon, Stones, Jefferson Airplane, etc.) is a master. Totally distinctive parts that absolutely make the songs he's plays on. Plays with a lot of rhythm too.
3) Billy Preston, of course (you know he's good when he's Ray Charles' piano player, much less the Beatles).
4) Steve Nieve (Elvis Costello)--saw the two of them live duo at the Ryman, amazing.
5) Chuck Leavell (more from his Allman stuff than Sea Level). "Jessica" is one of the most amazingly beautiful and well-constructed piano solos for my money in any rock song.
6) Booker T. Jones (amazing touch)
I like Jimmy Smith alot too but he's jazz. And of course Art Tatum--probably the greatest piano player of modern times. Fats Waller used to say when Art came into the room, I'm just a piano player, he's god.
I also hear that Mozart, Chopin and Beethoven were pretty good.