Avatar hands down, it takes like 10-15 minutes to get all 1000, but if you want to actually have a little fun - King Kong.

I quit using my mic outside of private chat/parties way back in Halo 2. The screeching younglings destroyed my slightest desire to speak to anyone in matchmaking, and by the looks of this thread - things have only gotten worse, or at least stayed the same.

My 1st 360 games were Gun and Perfect Dark Zero (I got it at launch). Gun was good, and well PDZ was... yeah.