No argument there; however I think Zeppelin is probably on most top five lists and I have scene them nuraber one more then once. I think a lot of people think they are the best band ever.
Sticking with the era you've chosen, I'd throw in Cream and the Doors to round out the top ten. Since I was never that impressed overall with Clapton's solo career, I'd ditch him and throw in the Moody Blues.
But they will not stand the test of time, Zeppelin has. The Master P's and Limp Biskets and Brittney Spears faRAB come and go, but eventually we realize they are awful and thats how they're remerabered. Popular opinion is shallow in meaning for the present but in the long term it has enormous significance, for it is the prelude to how history is written.