Best jazz or blues female vocalist ever

I'm a big fan of Betty Carter as a jazz vocalist,and Big Maybelle as an unbelievable Blues,R"n"B singer her Okeh Sessions re-released on Epic in '83 with "Rain Down Rain" and "You'll Never Know" "Whole Lotta Shakiin'" are required listening.

Stan, another great vocalist who has not yet been mentioned here is Anita O'Day. If you can get hold of the nine-disc set by Mosaic Records, you'll be in heaven.

Another vote for Sarah Vaughan

Ella of course, including a vote for best "scat" style.

Closer to this era, I have really enjoyed Kellye Gray as an obscure talent. Her "Standards in Gray" is a hugely overlooked performance. What I find interesting about Ms. Gray is that she also uses her voice as an instrument - with some remarkable chops I might add. There's a cover of "All Blues" on this disc with her doing the trumpet parts on vocal. That takes a lot of...guts. She pulls it off though, and she can scat too.

Sarah Vaughan had one of the great vocal instruments of the last century. That high bari to mezzo range of hers was peerless. She also had a bop saxophonist's understanding of harmony, phrasing and rhythmic development that so many emulate but none equal. Live, she would make you swoon with her sweeping, multi-octave portamentos. I witnessed the entirety of Carnegie Hall heave a communal sigh as she glided through an introduction of "How High the Moon". Still, she could mail-in lyrics from time to time.