Best jazz or blues female vocalist ever


Hello, I'm looking for some recommendations for a female vocalist (blues or jazz) from before about 1965. I think that Ella Fitzgerald and Billie Holiday are contenders for "best". Could I get some recommendations of vocalists? Also, what works would you say is their best effort? Thanks in advance.
talon4
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.
Sarah Vaughan, Ella, and Anita O'Day really do it for me. Carmen McCrae is also great.

I saw Anita O'Day a few years ago at the Iridium on Broadway, NYC a few blocks from where I live. Being in her 80's it was not the greatest, but I was thrilled to see her and there were a few moments when her old magic shone through. I never realized she was still alive.