The online has always been my problem with CoD. The online community is full of absolute shits and there's almost no variation in gameplay. In any given BF game, I can snipe, rush, pilot a chopper, wait in ambush, call in a mortar strike, ect. It depends on what you want. CoD is a great reaction and target recognition shooter, BF is much more team based and you can actually focus on small time tactics, especially with the new suppression mechanic they are putting in which makes lmgs more than an assault rifle with a massive clip and a really long reload time.
It's evidenced by the point systems. In CoD, with the exception of assists, most all the exp you get comes directly from your actions against the enemy, kills, capturing objectives. In BF I can just detect enemies for my allies, heal my allies, repair their vehicles, resupply their ammo, and I can get a ton of exp doing actions that don't directly hurt my enemy, but help my allies. It's the perfect war game for pacifists.