I know. I remember how great it was to wait ten minutes in a lobby to find somebody, then I get into a big group, possibly get another two friends on my friends list, and so on.
Although, I'd have to say that survival has an edge in some factors:
-Ranking up
-Better for split screen
-More challenge
-Maps are actually made for combat, not to tell a story
Best of all, to me, is the fact that you can't just run a circle for five hours to get to round 30. You actually have to keep moving, and if you decide to do a circle, then you're going to have to deal with all of those bullets wizzing over your head.