Linda Ronstadt

I'm not a fan of all of her work (for instance, the Riddle standards) but I have absolutely loved her voice for 50 years or more.  I had the pleasure of seeing/hearing her open for Neil Young in the early 70's and also witnessed a rather impromptu one-off performance where she was backed by Commander Cody and the Lost Planet Airmen around the same time.  Besides being my favorite female soloist, she's also great in duo situations, such as with Paul Simon ("Under African Skies") or Los Lobos' David Hidalgo ("El Chubasco").