I've played all the major games from GTA III onward. I only played the first couple of games so I could run around and kill police. I didn't start doing the storylines until GTA IV.
I mess around on some of the titles at times. Played IV, V, and SA. I'd say spent most of my time on V, usually doing stupid stuff. xD (Though I spent countless hours on Bully long ago. xD Different game, but still Rockstar's magic.)