The worst are the fans, ctually. They make me dislike the franchise. Got some CoD-kids in BF3 the other day and they were coomplaining that they weren't able to quick scope. Tsk...
The enemy is Activision, one of the worst publishers of the modern era. I recently purchased MW3 for 15$ used, since I sold BO2 and for what it is, it is fun, but it is just a huge copy and paste of Modern Warfare 2.