This was a tough one for me.. in the end went with" When the Levee Breaks"
Could have swore that I posted something earlier when I first saw the poll. I easily went with Levee. Probably my all-time favorite Zep track, or very close to it.
RnR also has a great drum intro, so no dissing that, but Levee has such a cool feel to it
When the Levee Breaks