Grand Theft Auto V and Vice City are my favorites. I spent a lot of time in both games and it was difficult to choose.
Vice City is one of the first games in the series that fell into my hands and was good for me for its novelty. Part 5 is the most comfortable game for me right now. Including because we play it with a company

I think I only played 2 and 4, maybe also 1, but probably just 2. I thought 4 was one of the most boring things I ever played, and I remember at least having a good time with the short time I played 2, so I guess 2.

V, but I don't like this game. I don't like any GtA game actually and always abandoned them after 3 or 4 hours, but I'm picking V because it had a nice set of songs to play even at launch which made my playthrough a bit less painful (but still painful)

GTA2, it had everything that made GTA1 great but imporved and LAN MP in GTA2 with a group of friends was always a blast.

I've only really put significant time into 1 and 3. Both good games. I revisit the first one fairly often, so gonna have to opt for that.

Vice City is the one I've enjoyed and had the most fun with, so that one.
I also have a soft side for GTA III, being my first experience with the franchise.
Other than that, nothing, ever since San Andreas this franchise has fallen out of my radar. I just dont like it anymore.

Bonus: None whatsoever.

San Andreas was the height of the series for me. Great big sprawling map with lots of fun missions. I did really like the story of GTA4, but it had too many annoyances to compete with San Andreas. GTA 5 had too many annoying shoot outs, I skipped most of the story missions.

What I would like to see is Hamilton, Ontario in the next GTA, based on the Musitano crime family and bring on the Canada bashing!

Even though I never beat it I have to go with Vice City it has the best soundtrack, setting and voice acting.

I know it's nostalgia speaking, but for me, it's Vice City.

As everybody here, I have a huge nostalgia for GTA Vice City (I mean the game has probably the greatest soundtrack ever in a game) but fun-wise, San Andreas (having big 3 different cities and small villages) is super great and GTA V is pretty much GTA V, so self-explanatory.

But I would say GTA Vice City as it defined my music taste since then (as I am a huge Hall & Oates fan)