I am a battlefield fan first and foremost. I haven't played through the campaign on either battlefield or MW3 yet. Multiplayer is my bread and butter.
I think the knifing in bf3 is pretty awesome, though. I like the realism, especially when you find somebody laying in prone to knife. I enjoy the battlefield series because it's huge maps, and you can really move tacticaly to make kills and save your butt sometimes. Whereas in the Call of Duty series, once someone shoots at you, you're pretty much dead meat. There is no going into prone or ducking behind cover. It's alot harder to get a solid shot on someone in battlefield, especially at range.
The only real reason I bought MW3 is because all my old army buddies play it online, and it's fun to catch up with those guys and do the tactical type stuff. But, I was really let down with the MW3 graphics. Looks and feels just like Black Ops to me. I would've been just fine if they have released all these new multiplayer maps in a huge map pack for Black Ops. Something I really dislike is I haven't found many good sniping positions on these new maps.
But, a plus for MW3 is they are going to release a new map pack each month for I believe 9 months. That'll keep things fresh for a while.
If any of you are playing on Xbox360, and want a casual gamer to play with or against, send me a friend request, and make sure you let me know you're from tinboats in the message. my gamertag is HundertLeichen.