Played loads on the COD4, and put in about 7 hours on the COD6 so far. I think I prefer the COD4, three simple choices for multikill, uav, airstrike and helicopter. Now everytime 30 thirty seconds on COD6 theres either a harrier shooting me, helicopters, stealth bombers or a turret gun! seems there's to many multikill perks.
Also i think you get closer games on COD4, it seems that once a team is winning in COD6, it's difficult to lose, and therefore difficult to turn around a losing game.
or perhaps i should MTFU.