Single player for sure. I've only played Online for about 12 hours and 9 of those were just a very meh experience. However, I've obtained 100% in single player about 2 weeks ago and there's not much to do. But the story for it made GTA V my GotY because it was SOOO fun!
Nothing is true. Everything is permitted.
2500th achievement: Black Ops 2-Mazed and Confused. 7-10-13.