Jessie J.
People are blinded by Adele's success but when it comes to raw vocals, JJ blow Adele out of the water. Adele's songs are not difficult to sing by any means, and 90% of the time, she opts to sing her songs live in the easiest way possible, may it be in a lower key or her choosing to go down an octave instead of ever hitting the higher notes she put on her studio albums.