John Paul Jones, Led Zeppelin...
here's why
Jimmy Page = The Showman
Ya, he's out there with his phallic symbol, a distortion pedal, and a violin bow...but any guitarist will tell you he's sloppy. That doesn't strip him down from being a rock god...that actually makes him more so.
Robert Plant - The Pretty Boy
Prancing around on stage in his two size too small jeans, golden locks, and crooning like a bleeding heart...amazing voice, awesome presence...but definetly not the leader.
John Bonham - The King
Seriously. Does anyone doubt he's arguably the best rock drummer of that era? While he may be responsible for some of the most rocking beats ever (and solo's), I don't see him directing musically in the studio.
Jones - The Man
Hands down the most learned of the four when it comes to music. Remember that jones and page met as studio musicians before coming together to rock the world. But as i said, Page is sloppy. I dare you to find me a clip or even a comment from anyone who has seen them live that says "jones was out of the groove...or hit a wrong note".
Not gonna happen. He plays all sorts of instruments (mandolin, guitar, bass, keys) and he plays them very well. Imagine if "Stairway" didn't have the organ in the intro...think about having no "No Quarter"...
Really tho...this question is kinda moot, b/c the greatest part of any great band is the fact that the members can come together and hash out this great music...no one man is an island.