I found myself buying a lot of PSOne games now in anticipation of owning a sytem that will be able to play them someday (PSOne or PS2). I mostly stick to the Square RPG's and such. So far I have FF7, FF8, FF9, Chrono Cross, FF Tactics, with Xenogears on its way (Metal Gear Solid as well).

What other must-haves am I missing? How about the other Square games (Vagrant Story, Parasite Eve, etc.) and other non-Square RPG's?

I thought vagrant story was pretty good, the story was pretty weak but the graphics and gameplay were top notch.

Dragon Warrior 7 is the one to get. This is coming from a guy who played and still own every single rpgs ever made. If you're willing to spend about $100 or so, you could get a dreamcast and skies of arcadia. It's one of the best next gen. rpg. By the way, enjoy Xenogear. It's a great game.

Your in luck man, PS is THE system for RPG's . You've got most of the good ones. I'd recommend Vagrant Story too, it was pretty cool but can be really, really, hard if you don't understand the battle system and how RISK works. Overall it is pretty difficult anyway but a blast when you get the hang of it. It looks like an hack and slash action game but its much different, quite unique. The cut scenes alone are way cool, the way they're scripted right from the intro is amazing. I would recommend these to you:

Wild Arms, it has some of the best music ever and a cute story.
I never got around to finishing Wild Arms 2 though, but its not bad either.

Dragon Warrior 7 is another must, I've been waiting to play another one of these for awhile, it will be the last great rpg on the PSOne.

There's also Lunar 1, and 2 which are both decent and come with an ungodly amount of fan merchandise I have eternal blue (2).

Xenogears is a nice one too, good story, nice music, really long though.

Suikoden 1 or 2
Star Ocean 2

I never really liked Parasite Eve but some people do.

I was about to recommend a DC so you can get Skies or Grandia 2 too but they're coming out for the PS2 so thats another option. Don't forget that Final Fantasy X is around the corner.

With so many RPG's to play I hope you have enough time to play them all, some like Xenogears are around 50 hours long!

I would recommend trying Lunar. I have both Lunar 1 and 2, but I like 1 much better. It's a very basic RPG with nothing too fancy, but the writing is extremely witty and fun to read. The graphics aren't a big whup, but that's ok considering that it was an old Sega CD game.

Grandia

Legend of Legaia

I enjoyed Wild Arms 2.

~Scheherazade

Dragon Warrior 7

Both Lunar games

Grandia

The Arc the Lad collection (whenever it comes out).

Valkyrie Profile

Final Fantasy Chronicles (with the original Chrono Trigger)

I can't wait for the Arc the Lad set myself. I'm a big RPG fan and that is probably the main reason I haven't bothered upgrading to a PS2 yet. All the best stuff is still on the PSone.

Tales of Destiny - Very SNES looking, but one of the greatest RPG's ever. Also pick up inal Fantasy Chronicles: Final Fantasy 2 & Chrono Trigger. 2 Awesome old school games. Final Fantasy 9 is my favorite though. Then FF7.

I recomend Suikoden, and Suikoden 2. The first is just average but was one the first RPGs for the US playstation. Suikoden 2 is really the gem in the rough, really overlooked. It has a great story and unlike 95% of RPGs it is really a sequel using over half the cast from the first (although different main characters). If you don't mind 2D graphics get these.

Recommended!
Suikoden 1 (haven't played 2)
Tales of Destiny (haven't played 2)
Lunar 1 & 2 (AWESOME!)
Parasite Eve (haven't played 2)

Avoid:
Guardian's Crusade
Beyond the Beyond

DRAGON WARRIOR VII !!!!

Suikoden I & II
Persona 1 (Haven't Played 2, but probably great also)

and of course DRAGON WARRIOR VII!!

When is Dragon Warrior VII coming out btw?

GET A SEGA CD! And play the original Lunar the Silver Star and Lunar Eternal Blue! Well, the PSX is almost the same... a few differences, but a great game.

Parasite Eve 1 and 2 a great also...

I like Vangaurd Bandits, but I also was a big fan of the Sega's Shining Force games...

Here is my (almost) complete list of ps1 rpgs. These are what I have and played:

Lunar:1&2, Persona:1&2, Saiyuki, Romance of 3 Kingdoms 6, Grandia, Vandal Hearts:1&2, Kartia, Ogre Battle, Tactic Ogre, Brigandine, Rhapsody, Vanguard Bandits, Monsterseed, Azure Dreams, Front Mission 3, Final Fantasy Tactics, Beyond the Beyond, Wild Arms:1&2, Jade Cacoon, Legned of Legaia, Thousand Arms, Tales of Destiny:1&2, Star Ocean, Valkyrie Profile, Suikoden:1&2, Legend of Dragoon, Parasite Eve, Xenogears, Vagrant Story, Chrono Cross, Final Fantasy Anthology, Final Fantasy Chronicles, Final Fantasy:7,8&9, Legend of Mana, Saga Frontier:1&2, Breath of Fire:3&4, and last, but not least, Alundra.

Of all these rpgs, I highly recommend Suikoden 1 and 2. They are my favorite of the whole lot. You can get them for about $20 apiece now too. Places like toysrus should carry them. Now, if you have other systems, I can also recommend some great rpgs for them.

Related question: what PS2 RPG's are worth checking out?

For the ps2, there are only 2 games which I think is worth you time. They are Kessen 2 and Ring of Red. These are strategy rpgs however. If you want a turn-based rpg, then you'll have to wait for FFX or Jade Cacoon 2.

The PSX versions of Lunar and Lunar 2 are better and a lot easier to find. Working Designs screwed up the Sega CD version of Lunar 2 by putting a stupid save penalty on it. It basically limited how often you could save the game by charging you each time you saved. It was a very stupid idea and was not put into the PSX version.

I also recommend Vanguard Bandits and Final Fantasy Tactics for that matter, to anyone that liked the Shining Force series of games.

Thanks for the suggestions.

Let me just say that pawn shops rock pretty good for getting deals on video games. I picked up Xenogears, Vagrant Story, and Final Fantasy Chronicles for $15.00 a piece. Pretty nice.