Tough choice. If we play them on the console it was released, the PS1 has about the same quality and much more quantity; BUT they are mostly unplayable by today's standards; slow ass battle systems, awful polygon models, eternal loading times, disc swapping, etc etc etc make most of those games a chore to play.
Snes RPGs were quick and sweet, so, I would take them any day over the PS1 games.
Now, if we include the abbility to use translation patches and emulators, the weaknesses of PS1 games disappear and the field is leveled, but then there are a ton of GREAT RPGs on the Snes that were never released in the west, so list thread:
Chrono Trigger > Chrono Cross
Tales of Phantasia >> Tales of Eternia > Tales of Destiny
Secret of Mana >> Seiken 3 > Legend >> poop > Secret of Evermore
Final Fantasy VI > FF IX > FF IV > FF V > FFVII >>> poop > FF VIII
DQ 5 > DQ 6 >>> DQ7
Star Ocean > Star Ocean 2
Tactics Ogre > FF Tactics
BOF IV > BOF I > BOF II > BOF III
PS1 had a lot of this games ported, but they generally played like crap. PS1 still has stuff like Wild Arms, which is surprisingly competent and fun, Suikoden, Vagrant Story or Valkyrie Profile, but Snes has Lufia 2, Ogre Battle, Mystic Quest or Robotrek.
Even if you count ARPGs, sure, the PS1 has Alundra or Legaia; but they don't stand a chance against Terranigma or Illusion of Gaia.
And you are still missing the Nintendo stuff, while not a lot, you have Earthbound, Super Mario RPG and four Fire Emblem games (and let's not start with the strategy games.
So yeah, both consoles have great RPGs, but the Snes wins IMO.