The GTA experience is largely determined by the mentality of the player. You can beat up and kill random people, but you don't have to. You can go around killing cops, but you don't have to. You're sort of stuck as playing the anti-hero archetype, but you aren't really confined to being
evil, per se. You can, if you wish, only kill "bad guys", only commit crimes against people who aren't really nice to begin with, and so on.
If you want to talk about games that really promote unChristain behavior, I can think of much worse than GTA. It's not even terribly graphic.
As to personal preference, I don't play the GTA games much because they get old for me. It's fun to play with someone else, tag-teaming in and out, but I've never been able to play through an entire game.
That said, Vice City wins major cool points by virtue of the awesome 80's music.
