Which GTA on PC should I play?

GTA III :P

San Andreas is the best by far.

I would recommend none.

gta vc is the best by far, and has the best soundtrack.

GTA: Chinatown wars... seriously now, San Andreas is the way to go

I would say play all. III is outdated but its the first 3D GTA so its a classic, Vice City has that great feeling to it (but you've played it already), San Andreas is the ultimate GTA sanbox, there was just SO much to do, especially since fans released sa-mp (multiplayer, you silly), and IV has the best story (and obviously better physics and graphics) and overall great feel to it too.
Now since I played V on xbox I will say: play that too, but keep in mind this game is made for multiplayer.
Single in V is fine but it feels that the game was made for online interactions and all that stuff :)

Story: Vice City
Gameplay: San Andreas

just play both of them.

I've not played 4 yet, but here is how I would rank them in order from best to worst:
GTA: Vice City
GTA 1
GTA: San Andreas
GTA 2
GTA 3

That's not to say that GTA 3 is bad, I just prefer the other parts in the series that I've played (note that I've also not played the handheld GTA, nor the expansion for GTA 1).

You should play GTA Skyrim, GTA Space Program or GTA Dreamhouse Party.

GTA London

Well personally i prefer:

San Andreas for the story line ( it al come togheter from VC and III ) and the big world with all its hidden secrets.

Vice City for the best radio stations, colourfull layout, icecream/drugs truck

III for setting the mark of 3D GTA

IV for showing that GTA is still the boss in it's genre, and the little dark but nice storyline and graphics of course.

V (not played yet :( )

You should play GTA 3 I think.
It's pretty awesome, definitelly one of the better GTA games (not AS good as Vice City, but still pretty good!).

Vice City is supreme. Best jokes, best gameplay.

So, you played the best game in the series. I'd suggest you to try GTA 3 and IV. They're really good. San Andreas is the most boring by far. You can also check the very first one but if you didn't play it earlier in the 90' it can be a bit harsh.

GTA 3 is okay but after Vice City, you can be dissapointed. I suggest you playing GTA4 and/or EFLC.

I'd go for either Vice City (Which you have already played) or IV, IV is my favorite because of its plot.

San Andreas had a great gameplay, but the plot was ok to say the least.

Truth is Vice City is best, I would go with SA or wait for V.

I would actually recommend Saints Row 2 over the rest though if you can get a console version or deal with a bad port.

As said San Andreas is great. And if you ever get bored, you can install SA-MP (San Andreas Multiplayer) and check Crazy Bob's Cops and Robbers server. That is one hell of a server.

What, are you kidding? ALL of them. Vice City has the best atmosphere and feel to it('80s retro style), San Andreas has he biggest explorable world and the most fun game-play and GTA IV has the best characters and story, as well as the most refined game-play(they went with quality over quantity, cutting out some of the things that made San Andreas as huge hit, but bringing the rest of elements to near absolute perfection). My personal favorite is GTA IV because I adore the story and Niko Belic(one of the best protagonists in a game...EVER), but depends on what you like most in a game, as all of them excel at something.