Final Fantasy 1-9 (except 3, I also don't understand why it didn't get released or re-released for PS1) and tactics. If you have a PS3, you can purchase 7, 8, 9, and tactics on the PS Store for 10 bucks each as a Digital Download. I bought 8 and 9 off of the store. Legend of Dragoon is also one of the best, in my opinion.
As for any other games though, I don't know many. I played RPG games 95% of the time during the PS1/PS2 era.