I love both artists ive GOT every SINGLE album of both artists! and they are both incredible artists Beyonce has 3 octaves Mariah has 5. Mariah is ace live and doesnt struggle to get out notes and Beyonce is ace live and doesnt struggle to get out notes.Beyonce has sold 11.2 million albums according to her RECORD LABEL! Mariah has SOLD 250 million albums according to her RECORD LABEL! Beyonce said she was inspired by MARIAH CAREY! and loves her! WE BELONG TOGETHER FROM MARIAH CAREY has been named the song of the decade! THEY ARE BOTH PHENOMINAL VOCALISTS!
in my opinion i think MARIAH pushes a little bit further with the MORE VERSATILE VOICE!
EVERY BODY KNOWS THEY ARE BOTH INCREDIBLE AND THERES NO DENYING THAT!

IN MY OPINION THESE ARE MY FAVOURITE FEMALE SINGERS.
1. MARIAH CAREY
2. Rihanna
3. Kylie minogue
4. Whitney Houston
5. Beyonce