Any vocals that you like?

Off the top of my head and not yet mentioned:

Aretha Franklin
Joni Mitchell
Tina Turner
Eva Cassidy 
Annie Lennox
Nina Simone
Florence Welch
Janis Joplin
__________

Bob Dylan
Elvis
Al Green
Jeff Buckley
Jackie Wilson
Elvis Costello (Best terrible singer award)
Ray Charles
Curtis Mayfield
Smokey Robinson
Elton John
Robert Plant
Sam Cooke 
Otis Redding
James Brown
Marvin Gaye
(Younger) Van Morrison
Levon Helm
Simon & Garfunkel