Edited list:
Michael Stipe is probably my favorite, but Roger Daltrey is the most powerful.
Jim Morrison, David Bowie, Dave Gahan
Bono-just listen to The Unforgettable Fire especially "Bad".
Kurt Cobain-just for the way he could howl his vocal chords out.
Pete Townshend, Ian Curtis, Robert Palmer, Eric Burdon, Billie Holliday, Bobby Darin, Joe Strummer, Johnny Rotten for his vocal sneering, and of course Lennon, McCartney, Harrison and even Ringo.