I had an in-law who was acknowledged. worldwide, as the Godfather of avant guard jazz piano.
He told me that he had never met a jazzman( and he had met them all) who didn't think
Sarah Vaughn was THE greatest jazz singer who ever lived.
He said musicians loved her because she was the only diva who could keep time as well or better than the bass player!
And unlike many famous singers you always knew she always never wanted to be doing anything else more than just singing with them.
You get a couple of Sassy recordings, sit down and really listen, and , unless you have really bad taste, your Cd's of Nora and Diane etc will end up where they belong, in the trash can.