Genji for the PS2 is in my opinion, always worth playing. Bushido Blade was one of my favourite PS1 games but its more of a soul calibur style fighting game, not RPG.
Genji for the PS2 is in my opinion, always worth playing. Bushido Blade was one of my favourite PS1 games but its more of a soul calibur style fighting game, not RPG.

PS1
Fear Effect and Fear Effect: Retro Helix were and are superb games!
PS2
GTA Vice City
Shadow of the Colossus

I never stop playing Vagrant Story on PS1.
You must play Intelligent Qube. Tobal No. 1, and if you can play imports Tobal no. 2 were great. For RPG's the best one is by far Valkyrie Profile and Suikoden II. (both are going to cost some serious penny if you are able to locate. Vangard Bandits, Koudelka and the Arc the Lad Collection are great as well. For some fun, throw in Parappa the Rapper and some UmJammer Lammy followed by some Bust a Groove 1 & 2.
kingdom hearts :D
For PS1 I would recommend,
FF7
FF8
Xenogears
Valkyrie Profile
Castlevania: SOTN
Parasite Eve 1
Parasite Eve 2
Sorry double post