They are both cool but i liked the fast pace in black ops. Just feels like it runs smoother and not as stiff as BF3. Im not a fan of those long BF matches taking about 45 minutes to a hour or being kicked by a childish admin. If you like fast paced, run and gun, easy to maneuver through your arsenal, black ops easy. If you like tactical , slow paced, tanks,planes then you will like BF. but as of now, for me I still like Black OPs 2 more.
is battlefield better than call of duty BO2? in battlefield its harder to get kills in my opinion
It depends what your game style is. I personally hate COD. It's a run and gun game where almost everyone just focuses on who has the best K/D (kill death) ratio.
I love BF3 because of the realistic aspect and how the main game modes aren't team deathmatch. For the most part, more people focus on playing the objective first rather than trying to get a ton of kills.
When you ask which one is harder to get kills, there really is no correct answer. Both games can be hard to get kills for some people.
If you're still deciding on which one is better, think about what you personally like in a FPS. If you prefer fast paced, run and gun matches, then get COD. If you prefer better realism and more strategy, then get BF3.