Most soulful female vocalist

FWIW, the first one that jumped to my mind was:
Billie Holiday.

It's Aretha Franklin,

Don't believe me? Take a listen at this vintage live Youtube video of her singing "Dr Feelgood" from 1968

http://www.youtube.com/watch?v=7ExOYgjzLnU

By the way, Lady Gaga gets overlooked and ridiculed by the audio enthusiasts here, but she is really very talented and has some soul in her voice.

Janis Joplin had a hugh soulful voice.

Eslaudio: "four loko"?? Is that a liquid, solid or smoke?

Lithojoe: I thought I was the resident smart ass around here but evidently I have some competition.

Alright... lets get one thing straight, Aretha Franklin is the Queen of Soul. You can talk about nuances and emotional response all you want, but you are embarrassing yourself if you think anyone, man or woman, can sing more soulful than Aretha Franklin. So lets just talk about who's in second place.

Lokie,yes, in the history of Soul, Aretha has no equal as the most soulful female vocalist. Those who don't know, don't know what they don't know.