Louis Armstrong, his gravely voice proves forever that it is the heart & soul that makes a great vocalist, the sound is important, but secondary.Bing Crosby, for starting a new style of singing (soft,intimate vocals, thanks to recording technology). Sinatra, best all around communicator, Little Richard, Rock and Roll incarnate. Elvis, croons and rocks. Johnny Cash, because he could carry the weight, John Lennon, the coolest channel for good in history. Caruso, even through those stinky recordings he sends out such a depth of power that you cannot help but be moved. BB King, the Rolls Royce of the blues. Steve Winwood, anyone else know a better recording by a 15 (16?) year old? than Gimme Some Lovin'. Ray Charles, you can rest in peace after you have heard him live! John Lee Hooker, a living part of American history. More than honorable mention to Nat King Cole. Strange choice of the day: Robert Plant, the most charming screech ever. It is said that the true measure of musical greatness is when a musician creates a new genre.