Which of these FEMALE SINGERS has / had the best singing voice?

note: i am NOT asking whose music you like the bets, just who has / had the best pure singing voice

adele

carrie underwood

enya

whitney houston

celine dion

mariah carey

christina aguilera

amy lee

linda rondstadt

donna summer

patsy cline

dusty springfield
Update: add karen carpenter to that list
8 answers 8