Ella Fitzgerald was probably one of the absolut finest jazz-singers that ever lived. Already at young age she recorded incredible stuff, where one clearly can hear her talent. Weirdly enough, it took a while until she got "really big"... of course because she was black.
(did you know that it was Marilyn Monroe who gave her a more than proper push into the "world-of-the-famous" ?!?!).
No matter what she sang; it was always a pleasure and joy to hear. even when the music wasn't so "good". I can imagine that many aspiring jazz-singer of today have Ella as their leading star. You can't go wrong with that.
Here you can find some of the songs she recorded. Transcriptions and/or arrangements.