Call Of Duty isn't an exclusive game, so it shouldn't even be mentioned. But Halo is, and you can't stop people from saying it. It is an okay game, in my opinion.
My favorite exclusive would have to be the Splinter Cell series. I started playing them on the first Xbox and kept on playing them throughout the years. It's a wonderful stealth/shooter game with an excellent storyline.
I know they're not exclusive but my favourites have to be
Just Cause 2, cause of it's awesome freefalling and open world gameplay Enslaved, the storyline and acrobatics are EPIC Burnout Paradise, nothing beats seeing a fully clean and polished super car faceplant the backside of a very unfortunate bus.
Fifa 11 is a very good game, it has good graphics if you make your own player. The sound of the game makes it seem like you're there. The announcers voices are awesome. And it's just a fun game to play.