I too have a legit disc-copy of SotN. I'm not going to be buried with it, but I definitely was stunned to find it at a local used game store. And you will get no judgement from me about Rhapsody--I strongly considered playing it once, but I think I got sidetracked by something else. I'll admit to playing Eternal Sonata, and enjoying it a lot if it makes you feel better. I also hated Chrono Cross, but mostly because the music was generally awful and you really couldn't understand the plot even with the "good" ending. I'm down fr some complex story, but they went way over that line and made it too convoluted to follow IMO.
As to (mostly) 2D PS1 games:
Breath of Fire 3/4--> BoF3 is most people's series Favorite (except Gideon and myself, obviously). The dragon transformations and class system are probably the best in the series, but the plot goes south near the end. BoF4 is a good, solid, traditional RPG, but it just never felt very much like a BoF to me. There is a plot twist that is really, really well done, but I play it as if it has no real relation to other BoF games, because it really doesn't.
Valkyrie Profile--> This is probably one of the few games I enjoy the voice acting for (just youtube some of the VA clips, especially Lezard), and that includes more modern games. VP has a unique take on Nordic mythology, and has a number of gameplay elements I really like. It also has one of the best difficulty settings on any RPG I've played. Higher difficulties mean less experience per battle, but you get access to more areas with potentially better equipment. There is no reason to play this game on something other than High difficulty settings.
Star Ocean: The Second Story--> While not the true Action RPG the later games are, this is by far my favorite SO game. The game systems are great, and I personally like the story a lot. I think the PSP version may be SLIGHTLY better, but I'm a real sucker for some of the cheesy in-battle VA work.
Grandia--> A lot of people like this game better than its sequel, but I'm not quite in that camp. The game is pretty good, with a unique leveling and battle system, but the plot kind of wanders a lot during the first part of the game, and there's some heavy-handed melodrama near the end. All said though, most of the meat of the plot is good, and it's really worth playing--again, there are some very worthy cheesy VA lines (almost everything from Gadwin, especially his "Dragon King Slice" line").
Tales of Destiny 2/Tales of Eternia : These are the same game, but when it first came out, NB ran into copyright issues with the He-Man people, so they change the name. This is probably my favorite Tales game--the battle system is the 2D action line system (or whatever they call it), and the artwork throughout is easily some of the best on the PS1. The story I think is underrated, and the game can be quite difficult at times if you don't know what you're doing. Definitely worth your time.
FF Tactics--> Now, I don't like this game nearly as much as some people (It steals a ton from Tactics Ogre, I pretty much hate the plot, and the ending is godawful), but this is THE strategy RPG IMO. This game basically spoiled me, and I can't really play many other SRPG's anymore thanks to how great the systems in this one are. Play it if you haven't, and you definitely won't regret (most of) it.
Lunar/Lunar 2-->OK, I may get some hate for these, because they're so linear, but I really liked them both. The plot is a little weaker in 2, but I like the battle systems in both, and really, the music is pretty great in both as well. I just think they're solid, well-crafted games that everyone who likes RPG's should play.
SaGa Frontier 2-->Not my favorite in the series, but the battles play out similarly to other SaGa games. There are a few different ways to spark skills in this one though, and it's not quite open world like some of the other games, but the art style is great, and there are some very memorable parts to the game. It's a bit of an unconventional SaGa (but not even close to Unlimited, so don't worry), but I think it's worth a try for sure.
Suikoden 1/2--> These copies are the Crown Jewels of my PS1 collection. I probably consider these the best games I've ever played (especially 2), and I really think everyone should play them at least once. Both plots, again, hem close to the 108 stars and "Bandits of the Marsh" story structure with some modifications. S1 is much more Asian in theme than 2 (which is more European IMO), and both tell stories that are absolutely worth experiencing. I am man enough to admit I teared up a few times in both games--the only real negative to these games IMO are the war games, which are much better done in 5. Still, for PS1 games, these 2 games are close to perfect.
I know others will mention a few games I left out (Dragon Quest 7 and Xenogears, among others), but I won't lie, I pretty much despise DQ7 and XG. I'll save the dissertation for some other time, but I personally cannot recommend them. *braces for incoming hate parade*