So I never had a Playstation growing up, and have been eyeing the PS1 Classics on PSN for awhile. Now that I'm feeling sick and just want to veg out while drinking a ton of vitamin C stuff, I'm feeling pretty inclined to buy one. My only problem is I'm not really sure which ones are really worth buying, so I'd like to turn to Giantbomb for help: which PS1 games are the best? 
 
The only two PS1 games I've ever played are Metal Gear Solid and Resident Evil, so I'm pretty much open to all suggestions. 
 
EDIT: North American here.

crash bandicoot 2 Cortex strikes back and 3 warped,  
 
first 
on  
your 
list!

Vagrant Story is on there right ? I'd say that one, if you're into RPGs.

Silent Hill, Parasite Eve, MediEvil, Resident Evil 1&2, Final Fantasy if you're in to RPG's, Twisted Metal 2.

Metal Gear Solid
 
EDIT:
Oh, you played it already, still, worth mentioning.

A tie between Spyro 1, Spyro 2, and Metal Gear Solid.

Xenogears

Klonoa: Door to Phantomville

Vagrant Story
Final Fantasy IX and Tactics if you don't have a PSP for the Tactics remake
Xenogears

DESTRUCTION DERBY!!! I got it with PS Plus, and it's awesome!
Also, RE 1,2,3, Silent Hill, Crash Bandicoot series.

One that has been mentioned yet is Grandia

FF VII-IX
Grandia

@Redbullet685 said:

DESTRUCTION DERBY!!! I got it with PS Plus, and it's awesome! Also, RE 1,2,3, Silent Hill, Crash Bandicoot series.

Oh god...it didn't hold up well, but back in the day that game was the bomb.

@Doctorchimp:  I've heard great things about Xenogears (and then been told the second half sucks or something). I find it interesting you picked FF IX over the commonly lauded VII. Is IX really the better game?  Also, is the first Dino Crisis any good? I remember being told one of those games was good. Hm. I think I'm going to have to start making a list for these suggestions.

Soul Reaver or Castlevania: Symphony of the Night are probably the best games not counting MGS.

Unless you want a jrpg, FF9 is the best.  That guy is a Doctor, listen to him.

You should probably mention if you are in Europe or North America because Europe has way more PS1 games on PSN, or at least they did in the first year or two that they were available. Maybe North America has caught up since.

I was actually looking at the PSN store today and I really want to get either FF tactics, Vagrant Story or Xenogears. I've heard those are some of the best ps1 rpg's. 

Spyro 2, Syphon Filter 2

Resident evil 1-3

Silent Hill

Parasite Eve

Dino Crisis 1-2

Metal Gear Solid

Crash Bandicoot

Metal Slug

Oh yeah, one more.  Alundra is awesome and on PSN.  One of my favorite PS1 games, but it slipped my mind.
It's like the older over-head Zelda games, but more difficult.

Parasite Eve

I thought I read somewhere that Breath of Fire IV is coming to PSN on the 16th or something.  
 
That one's pretty good.

Probably all three Final Fantasy series games, 7,8, and 9.
Chrono Cross
Vagrant Story
Xenogears
Final Fantasy Tactics
 
Obviously these are RPG's so only check them out if you are into them.

Silent Hill,

Castlevania SOTN,

Cool Boarders 3 (yea i said it),

Legacy of Kain: Soul Reaver

Syphon Filter 2

and Twisted Metal 2.