sims2 had a lot of content, but i love how perfectly sim3 is optimized. the game just runs great even on stuffty computers. it even recovers itself from crashes (MID crash) and continues without a loss in anything.
the game is just smooth. and you can go out and among the town without all the loving loading. you can get many things done all over the place where in sims2, you make a menial visit to a club, and your day is shot, and you go to bed to late to function for a week.