Top Ten Rock Vocalists

Arthur Wax
Arnold Grove
El Mysterioso
George Harrysong
George O'Hara-Smith
Hari Georgeson
L'Angelo Misterioso
Jack Lumber
P. Roducer
Spike Wilbury

Dekay - had to look those up...all pseudonyms for George Harrison, I take it.  Very clever.  

At the risk of offending...George, Billy Joel, Elton John and Mark Knopfler as candidates for a top 10 list of rock, hard rock, metal & prog vocalists have me scratching my head.  Each to his own, I guess.  

ghosthouse, the artists you just mentioned definitely are not hard rock/metal or prog.! But I think at least some of their music could be considered Rock.😎

This list mentions a lot of the usual suspects. If you want to focus on rock, it is worth mentioning the Seattle crowd:
Chris Cornell- Soundgarden
Eddie Vedder- Pearl Jam
Layne Staley- Alice in Chains
Mark Lanegan- Screaming Trees

I particularly enjoy Lanegan's whiskey soaked baritone on his solo albums.