They are all a great deal of fun. I'd say I like Vice City more than San Andreas, but I didn't really have any real problems with SA, I just though VC was more polished. IV is easily my favorite GTA, and ranks up there with my favorite 360 games. The graphics are beautiful, the city feels sprawling alive, and the missions are fun. Once you finish the game you can just smurf around or check out the expansions.

The one thing that bothered me about IV (I'm not sure if this happened with others in the series, I just noticed it in IV) is that whatever car/motorcycle you happen to be driving at any given time will have a ridiculous rate of occurrence on any given street. It kinda sucks to be driving a limousine and turn a corner to find at least 3 other limos on the same road as me.

I've never played Chinatown Wars but may check it out if I find myself with some extra dough.