That's tough because we also have Kelly Clarkson and P!nk, so I would add them and call it the top five vocalists of our generation. But Adele, Bey, and Gaga all deserve to be there. Their talent and influence is undeniable.
For starters Demi is an amazing vocalist. Just cuz y'all hate her and shes not as successful does not make her vocals any less. Kelly Clarkson and P!nk are better vocalists than Gaga too.
And who does, known Gaga-hating ATRL member Squall? I'm sure you're thinking Taylor or Katy, but desperately searching for another answer because you know you'd get your throat clawed out if you tried it.
The GP, critics, media, and so far ATRL agree with me. Wow!