Define 'pure vocal ability', seriously. Are we talking about always accurate intonation? Are we talking about melodic inventiveness? Harmonic sophistication? Putting lyrics across? There's a lot of different elements to being a great singer and different listeners weigh those elements differently.
If it's pure vocal ability then probably an Operatic singer like Dame Kiri Te Kanawa. If pure gold then Amy Winehouse.
Overall: Maria Callas Popular Music: Linda Ronstadt Personal favorites: Elizabeth Fraser, Lisa Gerrard, Kate Bush
Exactly....as I'd personally have different answers for each, as I'd imagine most would? Just the first names that come to mind for me but loads of others could be added: [Are we talking about] always accurate intonation? Barbra Streisand, Judy Garland, k.d. lang Are we talking about melodic inventiveness? Ella Fitzgerald, Nina Simone, Aretha Franklin, Yoko Ono (yep) Harmonic sophistication? Kirsty MacColl, Rhiannon Giddens, any of the McGarrigle or Roche sisters and their progeny Putting lyrics across? Marianne Faithfull, Nina Simone again, Carole King,
Sarah Vaughan would get top marks from me in all of those categories, FWIW, but there are lots and lots of fabulous female singers -- and those are just the ones I've heard.
Ella Fitzgerald or Linda Ronstadt. Ronstadt was just so versatile. In that respect there has been nobody like her.