Battlefield 3
Reasons:
1. playing on PC or console you get amazing graphics, massive maps, more content, DRIVABLE vehicles, more guns.
2: Black ops 2 has barely changed from Black ops 1, Graphics gameplay, frustration, besides the addition of a few new camos and guns your basically playing the same game.
3: Both of the Blops have been infamous for their douchebag, underaged, spoiled players, possible on uncommon occasions you will meet a person who isn't a fag, probably someone over 15 -_-.
4: Battlefield 3 requires alot more skill, and precision and more consistent aiming rather than ridiculously quick reflexes and 5 bullet kills with Blops2.
5: Battlefield 3 has bullet drop so sniping takes even more skill and precise aiming.
I'm not going to lie Battlefield 3 isn't perfect it does have some hit detection problems, this is easiest to see when your sniping. Though yeah overall Battlefield 3 is the better game especially when you buy BF3 Premium for 40 extra dollars you'll get bonus weapons and all the dlc that's come out and future dlc's to come.