Since I don't play on my Xbox that much since recently, GTA 4. I've played that game around five times, like I said, I don't play on my Xbox that much.
Edit: Saints Row 2 was a really fun game, so I got the first one aswell. Brilliant games. I like how they're completely different, the first one is hard and you don't get more money or better weapons later on, so the difficulty stays the same (if anything, gets harder). Then SR2 is just really stupid and is more for just fucking around in.