I'm fully backing SUPER on this one. The Mario and Luigi games are fun in their own right, but I wouldn't say either was superior to Super Mario RPG for the SNES.
I mean, really, the SNES one had it all:
- excellent pacing for a RPG making it easy to replay from start to finish
- some nice secrets if you don't feel like brisking through (Culex anyone?)
- great music
- diverse party of characters to play as
- the ability to pick up Mario and throw him at enemies as Bowser (I mean, how can you compare?)
- the neat side games along the way
All in all, I really loved Super Mario RPG. It was a great collaboration between Square and Nintendo, whose only real fault was that it could have been longer and that the Yoshi race was kind of a bore.