There are way too many. My favorite song is whichever one fits the moment. That said, there are a couple I come back to.
In My Time of Need - Opeth
In The Aeroplane Over The Sea - Neutral Milk Hotel
Girl Sailor - The Shins
Breathe Me - Sia
Black Cadillacs - Modest Mouse
Ocean Breathes Salty - Modest Mouse
All Time Lows - Hellogoodbye
For The Girl - The Fratellis
Right, I'm not going to be able to finish the list. I keep finding more.