As a rule I enjoy single player games as they allow me to play when I want, what I want, and stop playing whenever I want.
That's one of the main reasons I quit MMOs, I got sick of having to be online at this exact time for this or that "guild event" regardless of whether I felt like actually playing or not. The same can be said for more conventional multi-player games, I hate ditching in the middle of a game, it seems insulting to the other players, especially if they are real life mates, but honestly after a while sometimes I just want to watch TV for a bit or browse the web and go back to the game when I feel like, I suppose that makes me a bit anti-social doesn't it?