Ella Fitzgerald is widely considered to one the great female jazz vocalist. My Uncle Lloyd rated her the best by far. Nothing would sour him on a new singer more quickly than a reviewer who compared her to Ella.
I included Fitzgerald's Ella Wishes You a Swinging Christmas in my 2009 post on Best Jazz Christmas CDs. A Swinging Christmas was recorded in 1960. Scott Yarnow describes it as "a lightweight but enjoyable set of Christmas cheer." A Verve 2002 reissue has some bonus tracks.