I think Call of Duty Modern Warfare 2 is much better than Call of Duty Black Ops. I think the online play is much better, the campaign is better, and the only thing good about Black Ops is the Zombie mode.
I say that Call Of Duty Modern Warfare 2 is better than Call Of Duty Black Ops because there is better maps in Modern Warfare 2 than in Black Ops. (Also MW2 has a good weapon combination: UMP45 + Silencer = Death to everyone!)
I think the graphics on Modern Warfare 2 were slightly better than the graphics on Black ops. I was glad to be free of the noob tubing and the quick scoping bull crap when I switched to Black Ops from Modern Warfare 2.
Although Black Ops had the zombie mode back on it after World At War. I prefer Modern Warfare 2 because that game is just beast and so much more fun to play with quick scoping and throwing knife matches. On top of that its just got much better story line in the campaign mode. Modern Warfare 2 Wins.
I would go with MW2. Because ever since I played Black ops, It became a nightmare! First, on Zombies, people will just force you to open the door even if you don't have the points which is stupid. Second, my friends will not stop playing that retarded game over and over and over everyday without me playing a different game with them. Third, I got rid of it because it was boring. No offense, but it really was once you play a lot.
Modern Warfare was terrible. I've played each installment and so far, Treyarch is definitely better at the actual mechanics. Infinity Ward has terrible hit marks, weapons, and perks. I found with World at War, and Black Ops that if you shoot someone, they die. Not to mention the giant leap with melee like Halo's sword....Black Ops II is going to reign supreme and do what Future Soldier was supposed to do.