Vice City. It just has so much atmosphere to it. The one major flaw the game has is the toy helicopter mission, but other than that it towers over its competition. Though San Andreas is also a great game as well.

Lego City Undercover

None they are all shit

Ha, definitely the GTA killer. Combining GTA with the addictive stud collecting (bolt collecting of Ratchet and Clank) is pure genius. Best WiiU game, and between me, my kids and my wife, we racked up over 500 hours on it! Great use ff the game pad as well.

Yeah, it's like someone realized the formula for GTA can be done without sex, drugs, prostitution, murder, cursing and still be enjoyable.

Vice City is the best.
I would like to see a GTA VI in Rio de Janeiro.

Vice City, my interest in the series kinda plummeted afterwards. I tried IV but it didn't grab me in any meaningful way. Haven't given V a full try so I can't comment on it, every time I think of trying it I'm kind of apathetic. Maybe someday.

Mine would be Vice City closely followed by GTA3 and GTA2.

I only liked Vice City. Everything else is kinda meh and GTAV has such dated open-world design. Still felt like it used the outline of a PS2 era game. Some of the dialogue was just so cringe-worthy. The Series just is highly overrated. Much better open-world Devs and games out there.

San Andreas, that's the only one I liked enough to beat. Vice City would be my 2nd.