Iron Man 2 boasts best direction and dialog.
The American boasts best sound (the guns), and also has the best suspense... you will be so glad you are not in the very uncomfortable situation the lead finds self in.
The best performance is by Lennie James, playing an asshole detective in The Next Three Days. Runner-up is in the same movie, which is by the guy portraying the humorless security officer at airport checkpoint. My favorite performance, however, is that of Guy Pearce, who plays someone who can't create new memories and has to rely on notes, in Memento. The best cast is in Monsters, a movie which also boasts the best damage aftermath scenes.