I am a big Zep fan, always have been. People who saw some of their early gigs I've talked to over the years would not have considered their live shows early on "prime" at all. Some of the early gigs according to history were to fill in for the then broken up Yardbirds. These gigs they said were "primitive" compared to what we all saw at the midnight movies... the famous "Song Remains the Same" film of the renown Madison Square Garden gig.
It's a real shame that the so-called "Rock & Roll" hall of fame in Cleveland has almost nothing of Led Zep (at least when I visited) and had nothing at all from Queen when the movie about them was out. But they had plenty Whitney Houston, Madonna, rap, etc. Ironically, they had very little of Rush at the time, even though they got their start in America in Cleve thanks to WMMS, home of the buzzard.
I will go ahead and answer an inevitable question in advance. What was the best live concert I ever saw? Pink Floyd at Rupp Arena.
Most underrated concert tour I saw was Humble Pie/Mother's Finest/Mahogany Rush. Frank Marino retired from live touring sometime after he taped some gig in Cleveland around ten years ago (?) but they are on YouTube or can be purchased as a set of DVDs.
https://www.youtube.com/watch?v=4jUKJst-rUA