Gotta go with "Come and Get Your Love". A lot of the songs from this movie were new to me, but this one took me by surprise because: it's the beginning of the movie and it is just so catchy.
This movie introduced me to some great songs, especially "Fooled Around and Fell In Love" by Elvin Bishop. Such a great song. It was tough to choose C&GYL over FA&FiL.