Sorry to say Ive never been a fan of COD. There is something about being able to snipe at extremely long distances or say "screw it" and jump into the gunner's seat of a Combat Helicopter and rain fire down from above while avoiding anti aircraft missiles and lamp posts. :D
Add to that the amount of weapons and accessories you can choose from in BF3 compared to any other game on the market and there is nothing funner.
Dive into a building just in time to see a rocket or tank shell come through the wall. Or dive out of the building as you hear it creak and fully collapse killing anyone inside.