If I had to choose one I would go with Enya. But Florence Welch, Stevie Nicks, Kate Bush, Alanis Morissette, Carole King and Tori Amos would all be favourites.

Laure Le Prunenec

for modern pop I would go with Lexie Liu, super versatile.

all time Diana Ross

best female vocalist
 

Christina Aguilera hands down! 120%

best female vocalist of all time
 

The one and only Stevie Nicks ......Enough said

Whitney as for me