It's a tie: I might go with the OG GTA, just because even in a top-down form, I really appreciated the raw chaos and possibilities. And while I like all the 3d era GTAs, I would give Vice City special recognition. It came out when I was young enough that my mom had heard the news about it and didn't want me to get it, and I lobbied her until she gave in. (Including putting together a power point on why I should be able to get the game)