If i had to pick between Call of Duty Rinse and Repeat and Call of Duty Modern Warfare Rinse and Repeat, your really getting the same game.
Black Ops 2 = Futuristic and Zombies
Modern Warefare 3 = Somewhat in the Future and no Zombie.
I have played them both, but stopped outright buying call of duty games as of this year and in the future. I got tired of playing the game that just got a better render every year.
So if you had to pick, iwould go with black ops 2 because it would be the cleanest of the two.