This is a hard question! I basically love all of the songs... But if I had to choose my top five it would be:
(In no particular order)
1.) Haunted
2.) The Story of Us
3.) Back to December
4.) Mean
5.) Mine (I've listened to this song so much that it got a little old, but this used to be my favorite song in the world, so I thought I should include it.)

So out of that list, I would have to pick The Story of Us for my favorite, because I love the music video, and it's an awesome song to dance to!
Thanks abigirl07 for the question!