The Ikettes deserve a mention in this thread. Probably the hardest working girl group of all time. Take a look at the artists that took part with the Ikettes through the years...
The Ikettes - Wikipedia, the free encyclopedia
I defy anyone to come up with higher quality female singers than the ones listed in there.
I'm contesting Brenda Holloway being included in that list...as far as I'm aware she never sang with the Ikettes...one in the eye for wiki?
Here's a sample of the talent. (slightly dodgy vid, silly camera work only lasts for about 90 seconds in... the rest is not to be missed)
And this vid is worth watching through to the end, as it includes a great cover of 'Come Together' with an on form, charismatic Tina Turner.