lol, well, that made it easier to choose.
III absolutely blew my mind when it first came out; there was never anything like it before. Gotta give the nod to the one that started the 3d sandbox genre.
Vice City is the most memorable one for me, however. I probably spent this most time play it than all the others.
Sit tight! There is a very strong rumor that Rockstar will be releasing a souped up next gen version of GTA V! Probably will coincide with the PC release. Also, Watch Dogs will be coming to PS4 in May and that is very much in the same spirit as GTA.
[youtube]http://www.youtube.com/watch?feature=player_embedded&v=O-8hXr2sM84[/youtube]
Many report 5 will be coming to next gen and official announcement will be at E3