i dont really know how to rank them based on technique, as that's not something that i know anything about really
but here's some of my notes
Taylor Swift as a D+ is iffy to me. if Lana Del Rey can get a C+, i think Taylor can. I think she sings so much better when she uses her lower register, Back to December for example.
having Katy and Rihanna being the next 2 above her kinda surprises me because i don't think either of them have particular great voices, but have some really great songs.
as for Kesha's technique, i think she's better than she gets credit for, because she always uses so much stuff with her voice. i used to think of her as Lady T.Pain. but when it's just her voice, i think she sounds so much better. She has a version of This is Me from the Greatest Showman that really impressed me.
lana del rey over sia shocks me. i guess i really don't know technique because in my head, lana is a monotone singer for the most part. i'm surpised adele=lana on this ranking too. didn't adele get training in school?
and miley above everyone i mentioned above? wow. must be her technique because although i dont think she's bad as a singer, i prefer more of the C-voices to hers.
same with gwen, never thought she was that great, but never thought she was that bad. sometimes her voice is just weird to me.
and christina just sings doesn't she? has she ever taken a lesson ever? avril? that one surprises me too!
i agree with carrie and lea. i agree with all the A's. i think i might actually drop Beyonce down from a star to an A/B+
i'm thinking way too hard on this lol