Sure, we could rank these musicians based on their musical abilities and their contributions to the rock canon. Look, we definitely considered that. It's just that we considered their mustaches that much much more.
(Honorable mention goes to the mustachio'd drummer of ZZ Top, Frank Beard. He had the gall to be the only beardless member of a band famous for having beards even when his last name was "Beard.")
Guitar: Duane Allman
Go ahead, check out that stache. Look closely. At first glance, it's a beard, which would obviously lead to a prompt dismissal from the band and chastising from society. But a close inspection reveals not a beard, but a mustache that grows into the manliest muttunchop-mustache merger you've ever seen. No hair on that chin. No hair on that neck. It's like his nose grew a front yard but then expanded into the neighbor's property.
Guitar: Django Reinhardt
We've got to class up this band and Django's the guy/mustache to do it. When checking out his stache, notice the precision. Then notice the fingers on his hand. Yeah, they were been melded together in a fire. Many people discuss this in reference to his guitar playing, but nobody seems to mention he was able to perfectly groom his stache despite having penguin hands.
Bass: Phil Lynott
Drums: John Bonham
John Bonham's mustache once destroyed an entire hotel. Another time, it had an orgy with seven groupies while Jimmy Page watched in the corner. Many people referred to Led Zeppelin's sound as "The Hammer of the Gods." They were actually referring to Bonham's stache. One time he grew it out so much that it resembled a black dog, which would later provide the inspiration for the song,"Black Dog." When Bonham passed out during recording the song "When The Levee Breaks," his mustache filled in, laying down the legendary track. John Bonham's mustache was inducted into the Rock and Roll Hall of Fame in 1989.
Sax: Duke Silver
Vocals, I Guess: David Crosby
Backup Diabeetus: Wilford Brimley