Led Zep was there when the concept of "rock and roll star" was still evolving. I will grant that the Stones at least deserve honorable mention as the best rock and roll band but it's mostly because of their impressive touring record and Mick's superstar stage presence with his ability to put on a great show every single time he appears. And he's still doing it at age 60 for goodness sake! My point isn't that Led Zep necessarily had the best stage presence, just that they did have a true rock star sexual aura.
I could go on about Jimmy Page's abilities as a producer, and there are other aspects to their greatness like the length of time they were together without a change of band members. And the life they actually led as archtypical wild rock and roll bad boys equals the life led by the Rolling Stones in intensity, if not length. Both bands are perfect examples on an artistic level of what I call FORM = CONTENT, which in this case means that these two rock and roll bands personified the rock and roll life.
In conclusion, the above four categories do enough to fully qualify Led Zeppelin for my not-so-humble award. There will never be another rock and roll band to approach the stratospheric musical heights that Led Zep reached. The Recording Industry Association of America, who has the correct statistics, lists Led Zeppelin as the third best selling musical act/artist in history. The Beatles are first, with 166.5 million albums sold in the USA alone, Elvis is second with 117.5 million, and Led Zep is third with 106 million. I think it's very significant that those statistics are becoming geometrically times greater than the number of albums that they sold during their performance lifetimes. What has happened and is happening is that the young people of today are discovering them in droves because they are coming of age sexually and they recognize and connect with the most powerful musical example of that sexual power. They are buying their CD's, shirts, posters and other memorabilia. And frankly, I'm thrilled.