These movies put me in an odd position. On the one hand, I don't like Batman. It annoys me how much people wank over him and he really has no right to be as good at his job as any comic portrays him. However, Batman has had some of the best creative people on the planet work on his stories, and from A Long Halloween to the Arkham City game. Nolan's Batman films are among the group of media that makes me question my dislike for Mr. Wayne. Both Begins and Dark Knight are awesome movies, and probably count as my favorite for the genre.
Aaaaand in the other corner, the Avengers. I am in love with the Avengers. Iron Man and Thor are two of my favorite heroes, and I certainly rank Captain America and Hulk above Batman in terms of how much I enjoy their characters. Luckily, all four of those characters have turned in at least one solid movie going into the Avengers, however, I wouldn't really rank any of them except Iron Man as being in quite the same tier as Nolan's movies. And while I do really like some of Whedon's past work, I don't think he's as good as Nolan. However, off the top of my head I can't think of anyone who's better equipped to do this movie. I mean, if Nolan tried to do an Avengers movie, the tone would be completely out of whack with what has happened so far and would alienate a lot of the casual movie goers who are here for some fun.
So basically it ends up with a character I'm lukewarm on having a final installment of a so far fantastic trilogy vs. a group of characters I really like with pretty good movies going into a brand new experiment. The Dark Knight is honestly the smart bet, but I can't help it, I love the Avengers to much. Avengers, ASSEMBLE!