Gslone has it. April Lawton all the way. A true female guitar slinger. Too bad there was so little output before she returned to the graphic arts and then passed.
For jazz, Emily Remler. Plenty of output, but another jazz great taken by the needle and spoon. What a waste.
And for folk/pop, I must admit a certain weakness for the way that Shawn Colvin plays an acoustic guitar with the most violent, string popping, force and then takes it down to a more melodic level. Certainly, not the best, but a unique and easily identifiable style.