Lady Gaga - A
Katy Perry - A
Rihanna - A
Taylor Swift - A
Beyonce - A
Rita Ora - D
Demi Lovato - B
Lorde - B
Selena Gomez - C
Miley Cyrus - B
Lana Del Rey - B
Christina Aguilera - C
Britney Spears - A/B
Meghan Trainor - B
Carly Rae Jepsen - C
Adele - A/B
Hilary Duff - C
Zendaya - E
Avril Lavigne - B
Sia - B
Shakira - A/B
Madonna - A/B
Mariah Carey - A/B
Kelly Clarkson - B
Sara Bareilles - B/C
Kesha - B
Bjork - B
Janet Jackson - B
Justin Bieber - A/B
P!nk - B
JoJo - D
Hayley Williams - D
Ariana Grande - B
Cher - B
Ciara - D

As expected, this thread is a bit of an offtopic mess.
Closed.