Greatest rock vocalists?
Captain Beefheart
David Thomas
Mark E. Smith
...
Most of the 'classic' rock crooners have been mentioned so I won't go there, but curiously I don't think anyone has mentioned Rod Stewart! Seriously, Rod could sing rings round any of his contemporaries in his heyday. He may have become a bit of a joke in his twilight years (OK, since about 1975) but 'Every Picture tells a Story' is one of the top 'classic' rock albums ever made. Check out Rod's 'Mercury Years' compilation. Pure gold.
One of my favourites in the mid-seventies (and continuing the Scottish theme) was Alex Harvey of The Sensational Alex Harvey Band. A veteran rocker of the Hamburg curcuit (and inspiration for Lulu!) reinvented himself as theatrical prog-metal frontman in the 70's. 'Next' is probably SAHBs best album and certainly the best English language Jacques Brel cover ...
Apropos Jacques Brel – Scott Walker, Marc Almond, Jake Thackray and famously David Bowie have all tackled his stuff to varying success. Not sure if Scott Walker can be classed as rock either in his 60s crooner persona or later experimental work but certainly he was one of the greatest singers of all time.
Robert Wyatt has the most affecting and beautiful voice. From Soft Machiune and Matching Mole to his solo stuff and many many collaborations with other artists. A fucking genius and all round good bloke!
Blixa Bargeld rarely sings as such but has one of those voices (like Laurie Anderson) I could listen to reading the telephone directory.
Love him or loath him, no-one can sound as malevolently angry as John Lydon. And the first three PiL albums were works of genius.
Peter Perrett's petulant whine could be every bit as annoying as Lydon's but The Only Ones could do no wrong in my book.
But many great singing voices emerged from the ashes of punk:
Green Gartside
David Sylvian
Ian Curtis
Billy MacKenzie
Ian McCulloch
Richard Jobson