An idiosyncratic list. Apologies for including two to three in the categories; choices are hard to make and they all rate mention among the best.

American revivalists: Hally Wood, with Peggy Seeger a close second.

British/Irish revivalists: Isla Cameron. Second: Frankie Armstrong. Third: Maddy Prior, I think.

American early country: Sara Carter. I confess a manic fondness for the glorious Patsy Montana, not traditional at all, but one of the great voices of all time.

Blues: traditional:   Geeshie Wiley. Lottie Kimbrough.

Blueswomen, classic: Ida Cox, I think. near tie: Ma Rainey. 3rd: Victoria Spivey, Sippie Wallace, and Bessie Smith is of course in there somewhere too.

American traditional: It is very hard to beat Cousin Emmy (Jo May Creasey) of Kentucky, though she made her career primarily singing non-traditional songs.

Purer American traditional: the "Barbara Allen" of Rebecca Tarwater (Library of Congress) is priceless. Lena Bare Turbyfill Brockwell (Library of Congress). Lily Mae Ledford certainly. I feel I'm leaving out two or three that haven't come to mind. The greatest current Appalachian traditional singer I've heard is Elizabeth LaPrell.

British/Irish traditional: being a yank I'm less of a judge, but: Sarah Makem. Belle Stewart. Triona na Dhomnaill. I know I am leaving out others that I haven't thought of.

Heartfelt best and grace notes to every one of them. Bob