I played both MW and BF3 How ever i dont enjoy them a great deal, I used to play COD1 Rifles only at a pretty high standard.. The cod series since the first just makes me sick at the lack of skill/aim/game sense required to be good at it.
Back in the days when you had to actually aim at their heads to kill them in a single shot, rather than spray a clip of ammo into a corner of a wall and drop 8 people. /endrant
CSS is quite good due to bullet penetration being way less effective, only works on boxes ect rather than shooting though brick houses.