Modern Warfare 2 was one of the worst games I had ever played. Its Campaign was short, its Spec Ops was boring, and its Multiplayer was ridiculously unbalaced and full of little kids. The fact that no one took me seriously in expressing this opinion only caused me to hate the game -- and the studio -- even more.
Black Ops, on the other hand, was a pleasant surprise. I didn't want it, but my brother bought it. Its Campaign was quite a bit longer and more interesting. Its Zombies mode was my favorite survival mode ever. And its Multiplayer, though I still wasn't a fan, was at least more balanced.