Black ops or Modern Warfar 2?

so i don't really know which call of duty game to like more...black ops or modern warfare 2 because i believe both games activision were proud off in the end but their has to be one in particular which is the fans favourite
personally i think cod modern warfare 2 has more efficient and better graphics, however, i aslo know that black ops has a more challenging campaign mode with new maps added to the networking system
and modern warfare 2 didn't have zombie mode like black ops did which makes the game more spiced up and epic and it's more harder to complete then the previous zombie mode-in world at war
so what do you think guys

i love more mw2 than bo...