Hard choice, I'm going to have to say Playstation one followed closely by the Snes. As a previous poster said, it was pretty much the 'golden age' og JRPG's, when they were actually good. Final Fantasy 7, 8 and 9, Suikoden 1 and 2, Star Ocean 2, Wild Arms, Breath of Fire 3, Grandia and Alundra are a few examples of the excellent JRPG catalogue the system had. Then you had the excellent fighters like Soul Edge/Blade and Vampire Saviour.
The Snes of course has a sizable library of exellent games
Then it's the Genesis and so on.
The Saturn wasn't too bad either really, with games like Guardian Heroes, Nights (and of course Christmas Nights) and Burning Rangers. Very good for 2D games as well.