There is too much. Basically all the games from tens of genres, search for the JRPGs, fighting games, 3D platformers etc and you'll find lots. PS1 has the 2nd biggest library I think, behind the PS2.

There are obviously lots of great PS1 games. The Japanese library dwarfs the US/PAL library, but even those are intimidatingly large.

I personally collect PS1 games that I actually want to play still. My problem is that most of the 3D games have aged poorly and are now, naturally, available in superior versions/sequels elsewhere.

For example, some of my favorite PS1 games late in its life was the Tony Hawk games. With those, the Dreamcast versions are vastly superior, or the THPS 2x for the original Xbox. Both are better options when wanting the relive the series now.

Another example of a game that I liked at the time was Marvel vs Capcom. With that, both the Saturn and Dreamcast versions are superior.

Luckily, because of the size of the library, even with excluding games that are available in better versions elsewhere, I still have about 50-100 title that I want to get.

For some cool Japanese games I would recommend Pepsiman, Harmful Park, Sexy Parodius, Gals Panic Silhouette Stories, Toaplan Shooting Collection, etc.

No one has suggested Star Ocean: The 2nd Story yet? What the fuck you guys!?

Besides that masterpiece, I would suggest Tomba!, Kartia, Threads of Fate, Street Fighter Alpha 3, Mega-Man Legends 1 and 2, Grandia, and the Arc the Lad Collection.

What do you plan to play these games on? I would suggest playing on the EPSXE emulator. 95% of the games look and run so much better, especially the 3d ones.

Also, I like that you already have Xenogears in your short list. You won't be disappointed.

I've barely played any PS1 games (Only Spyro 1 & 2, Crash 1, and a couple of minutes of Tomb Raider), but I would probably give the Resident Evil games a shot.

some games are now very costly I need to get ff8 and ff9 back . I have 6 and anthology

i actually have one game that I can never verify the price as I can never find any copies on eBay. its literally called "one" side scrolling contra style shooter. does anyone have any idea if its rare

I plan on playing them on my PS3 :P.

Sexy parodius was good;

https://www.youtube.com/watch?v=28jNCeXBe18

I liked the colony wars games, absolute amazing graphics for the time;

https://www.youtube.com/watch?v=079423NZddg

Duke Nuke 3D Total Meltdown
Einhander
Ready 2 rumble boxing
Wing Commander games (I liked them and they had big budgets and great production values for the time)

Get Ape Escape and the Spyros. Also get Tombi.

And don't forget the wipEout games (if you must choose one, it has to be 2097).

How the hell did I forget about the awesome Sexy Parodius? Shame on me!

Gotcha. The smoothing is okay on the PS3, but EPSXE is the way to go if you're ever interested. Some of these games are just really hard to look at.