Right now I'll say PS2 because of how redundantly diverse it's library was. I didn't even play that many RPGs that generation because there were just so many amazing things happening across so many genres. Well into the PS3 generation I was still trying to catch up on masterpieces from the PS2 gen.

If backwards compatibility counts, PS3 takes it. It had good games in its own right but I also played my PS1 and PS2 classics as my 60GB had native backwards compatibility. I also got a SNES emulator running on it back when the PS3 still supported Linux.