In my Opinion it's Kingdom Hearts II it's a pretty Awesome RPG, It's like an action-rpg-fighting game put together in one game! Plus it's pretty long... FF VII and FF VII Crisis Core were both pretty great too!
Everyones going to say FF7, though I seriously doubt that half of these people have even played Final Fantasy. Go download an Emulator, and FF7 for your comp, play it, beat it, and than we'll talk.
I liked old school Ultima Online. Nothing will ever come close to that for me. Old school meaning 1997 or 1998'ish. After that it was ruined. No RPG has ever done it for me like UO. Although WOW came close.
