I turned all of my PS1 games into isos a few weeks ago and now I'm playing through some of them. Vagrant Story, Grandia, Star Ocean 2, Legend of Mana, Persona 2, Shadow Madness, Legend of Legaia, Xenogears, and maybe a few others. I pretty much bought every PS1 RPG that ever existed back during the late 90's.

Vagrant Story is pretty cool, but it gets bogged down when enemies start to appear with insanely high defense.
Legend of Mana is a nice, laid back game with some amazing backgrounds. I wouldn't put it on any "Best Of..." lists, but it's a game that's got a special place in my heart for whatever reason.
Legend of Legaia I haven't played very much of just yet, mostly just part of the intro to make sure it worked. I really liked it back when it first came out though.
Star Ocean 2 is one of my favorite PS1 RPGs and one of the few that I actually beat. It's weird, but I really, really liked RPGs but I'd hardly ever finish them.
Xenogears is another that I really like. I think I've made it really close to the end of the first disc about two years ago when I decided to play it again and see if I could finish it on my own [I watched my brother play it all the way through back in the 90's].
Grandia was one that I nearly finished. Towards the end it got really hard though and I had to use the Gameshark to cheat my way through it, but I upgraded to the PS2 and the Gameshark disappeared before I could beat it. Gameplay's okay, but it's the soundtrack that really stands out. Noriyuki Iwadare is a master of music. Has he even done any soundtracks recently?