Logan. IMO, The Avengers is primarily great for what it accomplished. Don't get me wrong, I love it, I think it's peak popcorn entertainment. But it doesn't hold up as well against films outside the genre like Logan or TDK do. Jackman, Stewart and Keen deliver brilliant performances, the production design is exquisite, it's bleakly beautiful. And its moved me emotionally more than any other Comic Book Movie (And most movies in general).
Also, shameless plug here, y'all should totally head over to my Christmas Movie Tournament and vote there, too.