PS1, quantity and quality. You can make a Top 100 games entirely filled with PS1 titles. N64 was like the Wii U, just a handful of good games.
PS1 games also have aged better than N64 games. N64 games look blurry and muddy with a limited color palette. PS1 (and Saturn) games are pixelated and have more charm.
The "N64 look" is just weird and doesn't hold up, there is more detail with bigger worlds, but they look like they want to be Dreamcast games on a far inferior hardware. They look like games in beta stage on a early Dreamcast prototype, that's the best way I can describe them.