I don't have just one favorite, but a couple (no specific order):

"Salty Air" by J. Viewz
"Sprawl II" by Arcade Fire
"Crave You" by Flight Facilities feat Giselle
"Causers of This" album by Toro y Moi
"Feel It All Around" by Washed Out
And Finally "Barbra Streisand" by Duck Sauce

Songs I've been repeating since summer.