My favorite PS1 game is Final Fantasy IX. No question. It’s my favorite RPG ever made, being a perfect example of what the system could do at the end of its life, while presenting a world filled with memorable characters, very honest writing, tons of things to explore, and a political thriller of a storyline (kind of. Sort of. I liked it. :3)
Other favorite titles for me are Vib Ribbon, the entire Ridge Racer lineup, Spyro the Dragon, Jumping Flash, the entire Namco Museum line, TEKKEN 3, Klonoa: Door to Phantomile, Mega Man 8, Mega Man X5, LSD Dream Emulator, Resident Evil 2, and more!
Best part of PS1? You can have a AAA title and a weird, experimental, low budget title on the same shelf and they feel perfectly normal next to each other. PS1 was a weird, lovable, professional, and majestic console that is one of my favorites.