exceptional voices of female singers (non-classical)


What I'm talking about here is what critics of classical singing refer to as "the instrument": the exceptional beauty or uniqueness of the timbre of the voice qua voice.  For the moment, put aside preferences w.r.t. repertoire, interpretation, performance, style, delivery, etc., and just consider the *sound* of the voice.  We're *not* talking about favorite female artists here, because that kind of preference is based on a whole amalgam of factors.

I suspect some of the top figures in the category I've tried to define often aren't very popular among audiophiles, because of those many other factors.

My first three nominations: Barbra Streisand, Linda Ronstadt, Eva Cassidy.

128x128twoleftears
Great question., most surveys by highly regarded voice coaches consider Karen Carpenter the finest contralto voice ever recorded. Just released complete set of new vinyl albums.  Feb 4 will be 35 years since she died.   
These are the only ones I've heard who belong in the top tier of "as close to vocally pure as possible".

Ann Wilson
I saw her in concert in her prime and when she sang Dream of the Archer it just sent chills through me. She lost it by the late 80's.

Oceans of Slumber's Cammi Gilbert
Check out their song Sunlight (Live) on Youtube, or their new song The Banished Heart
(caution: Metal, but I think most can handle it. It's mild.)

Bonnie Raitt
I don't know why her voice sounds so much better on ballads, but her rendition of I Can't Make You Love Me is stunning. Adele attempted this song and butchered it. Only Bonnie can pull it off.

Whitney Houston
Celine Dion
Not my style, but I appreciate their stunning talent.
Thanks @bdp24 for recognition of Darlene Love. She never gets the recognition I think she deserves.
So many great nominees, and a few new to me.I'll have to do some research.
A few I didn't see:
Bonnie Dobson, who wrote and first recorded Morning Dew.
BONNIE RAITT, or did I miss her?
If you've never heard the all-girl group, ISIS; Carol MacDonald has a delicious contralto.
Speaking of contraltos, Chrissy Amphlett of the Divynals, Amy Winehouse, Johnette Napolitano of Concrete Blond..Luv 'em

Did we miss Margo Timmins of Cowboy Junkies?

There are too many amazing background singers to mention; but the Blu-Ray of 20 FEET FROM STARDOM covers many of them.
Of special merit are Clair Torey (Great Gig in the Sky) and Merry Clayton (Gimme Shelter). Rosemary Butler is another fav.

I don't know if we can count her, because she is an opera singer; but Olivia Safe contributed such amazing vocals to Jeff Beck's SERENE, that I thought it was a synthesizer. Never heard anyone hit the highs she does.

Three I am rooting for:
Nicole Atkins
https://www.youtube.com/watch?v=lefhIHdWs3I
Frazy Ford for her unique sound
https://www.youtube.com/watch?v=PXRrySTujn8
Bonnie Bishop, an evolving talent.