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
Gentlemen, Thanks again for all the great responses. I've just ordered two cds... "Sarah Vaughan with Clifford Brown" circa 1954 Universal Records (Japan) & "No Count Sarah" circa 1958 Mercury (Japan). Both are recent Japanese remasters. I'm looking forward to hearing them. Too bad the Japanese remaster of "At Mr Kelly's" circa 1958 was backordered. I thought that that would be one of her better releases. I plan on buying a few cds every couple weeks. Shirley Horn and Anita O'day are on my short list, among others mentioned. Best wishes, Stan
She's none of the above, but give either of Julia Fordam's first two cd's a try and you'll see why her 19 year old cd Porcelain made Stereophile's "Records to Die For" this year.