Watching how Robert Pattinson and Kristen Stewart won their third consecutive MTV Movie Awards 'Best Kiss', I was struck by how they can win for ten years based solely on popularity. Yes, they look amazing together, but it's not too much acting in it by any stretch. They have been dating for a long time now. So I personally go with the one kiss that deserved it more. Both Portman and Kunis had to act out an aggressive scene in the movie "Black Swan".
Or if you prefer the full scene, here goes below.
Black Swan makeout scene