Both have such a huge library of fantastic games. In my opinion, the best libraries overall of any generation of video games. I think they existed during an era of video game development where there the market had not fully digested what a commodity video games could be, so there was space for a lot of experimentation and discovery. Off the top of my head, the SNES has...
- Donkey Kong Countries 1, 2, and 3
- Final Fantasies 4, 5, and 6
- Super Mario World
- Yoshi's Island
- Super Metroid
- F-Zero
- Star Fox
- Mega Man 7
- Mega Man X, X2, and X3
- Breath of Fire 1 and 2
- Rock and Roll Racing
- Earthbound
- Secret of Mana (and sequels if in this hypothetical we're not being region-locked)
- Secret of Evermore
- Terranigma
- Skyblazer
- Hook
- Street Fighter 2 (and others)
- Final Fight 1, 2, and 3
- Killer Instinct
- Super Mario RPG
- Joe and Mac 1 and 2
- Soul Blazer
- Chrono Trigger
- Zelda: A Link to the Past
- Mario Kart
- Shadowrun
- Demon's Crest
- Super Ghouls and Ghosts
- Castlevania Dracula X
- Super Castlevania 4
- Mortal Kombats 1, 2, and 3
- Illusion of Gaia
- Dragon Quests
- Star Ocean
- Lufia
- Front Mission
- 7th Saga
- Ogre Battle
- Harvest Moon
- Tales of Phantasia
... I'll leave it there, but the list goes on, the SNES has a library that is burgeoning with bangers. The PSX is, too, but I feel hesitant to ruin the comments page with another list.
Either SNES or PSX