Jungleland without question.
Was a sophomore in high school near Springsteen's hometown of Freehold, NJ when Born to Run was released in 1975. I was just a couple of years too young to have seen him locally before his popularity exploded, but my sister used to see him down at the Stone Pony in Asbury Park.
Heard every song on that album 14 million times during high school and never tired of it. Moved to CS in '78 and saw him in concert in Austin when I was at A&M, but haven't been a big fan since Darkness on the Edge of Town. I thought The River and Nebraska were simply meh, but gave him a pass thinking he was just going through a phase. Born in the U.S.A. was utter crap and I haven't actively listen to his music sense...
but whenever I hear someone play his early stuff, I'm transported back to summer nights down the shore...