Back in the 1990s Ms. Carey was considered to be quite the singer, but she is not my style or type of music...
The line I quoted was one of several cited quotations in a section on Callas called “The Callas Sound”. I just went to Wikipedia for the quickest route to what I thought was common knowledge: that her voice is not considered technically impeccable. It's not my opinion or Wikipedia's opinion ... it's the consensus. Sure, put her up as “greatest” vocalist if you like (many would) but in this thread it's like saying that Ella wasn't the most technically gifted female vocalist because that accolade should be given to Nina Simone or Billie Holiday. If you're wowed by Nina, Billie, Callas or (I'd add) Judy Garland to that list (or Edith Piaf for that matter) then you're responding to something other than technical ability. You won't have to search far to find articles on Callas's technique but here's one from The Guardian: Maria Callas: The truth is she was far from perfect. And NPR has a piece on “Maria Callas: A Voice of Imperfect Perfection”
I certainly would not consider her one of the "greatest" female vocalists ever, but damn, Lynn Carey has a great set of pipes...and other attributes too! Check out her version of "Ain't No Sunshine" which kicks off the 1972 "Preserve Wildlife" album. On a side note, the album gatefold opens up to display Lynn & a lion cub in a provocative photo!
All-around has to be Aretha. She could sing anything and deliver magic. My personal favorite is Billie Holiday. Not a great technical singer and limited range but, my lord, what musicianship. She's the Queen.
I prefer someone who can do it all, has absolutely massive range and can really bring it. That's Baby Jean Kennedy...
This is an impossible question, but if there're eight pages of replies accepting or even considering the premise that it can be answered how is it no one has said Marion Williams?
pure vocal ability - linda ronstadt - i'm not sure exactly how many other female singers did as many different styles as she did, but she is absolutely right up there. as for 8 pages of greatest female vocalists of all time.....sorry, but just naming someone who hasn't been mentioned to pad a post count is not the wat to do things. you can most definitely narrow this down to 10 - 20 total singers and then take it from there.