Klonoa, which just got a remaster for pretty mich everything. It's a cute sidescroller in a 3D world, and has some pretty interesting themes (opposed to the stereotypical grassy level, water level, fire level, ect).
Also Wild Arms 2 on PSone is way better than I was expecting. Been playing it the past two days. I feel like every RPG on the PSone gets overshadowed by FF7. My favorite action RPG on the system is Thread of Fate.