well itz hard to say but if you chose a highfy graphics then battle field and if you are a fan of strategic and online death matches with friends then black ops is great without any doubt ..
I prefer Battlefield that's for sure, I don't like the multiplayer of call of duty, it looks too cartoonish with all the stuff going on the screen. On battlefield there are some things on players, but it's small and discreet. Totally unlike on cod.
i would say COD all the way... they are coming out with a new call of duty black ops 2 as if anyone should be surprised. I am not sure if it will be black ops 2 or iron wolf, I have heard it could be either or but it will be a sequel of black ops for sure. I cant believe that MW3 did beat the sales of Black ops, I think Infinity Ward games are much better than Treyach... just my opinion though
I've finished the solo mission in battlefield 3, good story, good scenery, lots of different things to do in terms of missiongs. Now I go back to multiplayer, nice too, but I wish they'd release GTA V soon now