It might be interesting to share and hear other's choices for favorite female vocalists. List as many as you'd like, any genre, etc.
I may not enjoy the music of some vocalists, but the voices can't be discounted. I wonder how many I'll read and think, "How did I forget her?"

For soul/R&B, I've always loved Aretha Franklin. Such a powerful, soulful voice. There are so many great soul/R&B women, we could dedicate a thread just for them.

For jazz, I think Lena Horne comes to mind first. Ella Fitzgerald has to be mentioned as well.

For rock, I like Ann Wilson of Heart. She sounds better now than in the 70's. Strong pipes with a voice that is incredible. I also liked Grace Slick when she backed off the power. I can't forget Pat Benatar and her multi-octave voice.

Stage and opera goes to Sarah Brightman. When I hear anyone else try to sing any Phantom of the Opera songs, they come up short by a mile. Simply one of the most beautiful voices ever.

Speaking of most beautiful voices, Barbra Streisand, The Voice.

Annie Lennox. Period.