Now this really does depend on mood...

http://youtu.be/ZFvQ3bWLQBo
If I want my classic-era rawk all mindless and loose, then it's The Who hands down.

http://youtu.be/O0OPKywMoSk
If I want it tight, technical and proggy, then I go for the Zep.

...I didn't vote because I love them both equally.