Top Ten for whom? There's takers for even Jimmy Durante.

The legit voices are different from the pop voices and the trad folk voices.

Then there's the singing groups. Andrew Sisters, Barry Sisters, King Family, Take Five,
Manhattan Transfer, Ink Spots (mentioned above), Swingle Singers, The New York Jazz voices,


Hey, Fred Astaire could sing. Popularized a lot of songs from the 20's and 30's.
Johnny Mercer.

This "can" sing business is highly subjective and has to be defined. Legit? Bel Canto?
African-American? Middle Eastern? Asian? Indian? Blues shouters? (Ma Rainey, Bessie Smith), Irish trad?

Not sure where this thread is going but at least it brings to mind many singers who
have left a lasting impression on their audiences.