Its almost a tie between Cough Syrup and Teenage Dream (Acoustic version) but Cough Syrup wins out for me. Yes they are are both done by Darren, but When Cough Syrup came out I couldn't stop listening to it. On my Itunes account its at 687 listens (688 after i finish this cuz now i have to go back and listen to it again). There is just something about it that makes me listen every time. I've never skipped it when it comes up on my Ipod and i always have to listen to it at least twice. I'm not sure if its because of what it was used for in the show, or because it just kinda haunting sounding in its own, but i just cant get enough of it. Its like a siren song.