Hard to say which is the worst Zep album. The hardest part to admit is studio magic is what made Zep so good. I am sure younger Plant had much better chops but overdubs and good editing make him sound amazing. While Page is credited for writing some great riffs/tunes he is not a guitar god in the technical sense. Watching live performances is painful...poor sloppy playing/missed notes/cues etc. Page is great at making a studio masterpiece. It’s easy to see how drugs/alcohol affected him playing live. I get that bands like to mix it up live as it would get old playing the studio version note for note every night but there are some solos/ parts you don’t mess with as they are too perfect/iconic. But when you do and do it poorly it’s pathetic. It’s almost sad in a way to know that Zep really could not duplicate live what they could in a studio.