Mothership - The Inspiration

Deep Purple "Machine Head"

Purple was as close to Zeppelin as anyone ever came. They were recording at the same time as Zep, so they are both from the same genre. Deep Purple “Burn” is also an excellent album (albeit, recorded by a different version of the more popular Machine Head era “Mk 2 lineup”).

Ritchie Blackmore is every bit as exciting a guitar player as Jimmy Page. Check out Deep Purple.

...and you gotta include Jack White's other manifestation as front man for The Raconteurs. In the "Consolers of the Lonely" album, he basically shows off that he can do Plant better than Coverdale ever DREAMED of! All the resonance, and "right now" intensity that made Plant (and his obvious inspiration J. Joplin) the best vocalist ever...
There's been better "singers"; but voice as an instrument? Plant. Hands down, the best ever.

White Stripes are pretty good based on listening to the album preview on Amazon.

yeah, Rory Gallagher.

Another vote for the White Stripes and Jack's different excursions, latest being 'The dead weather' and the album is 'Horehound'. You will love this.