All of their 音楽 is basically the same, but I think Demi has the strongest vocals without autotune so she's probably the best live and Selena Gomez can't sing for shit so she's the worst.
Demi has very strong vocals. Miley has a sassy voice, i like it. Selena has high-pitched voice, she can't sing well. So i'll say demi has the best voice
They all suck and their 音楽 isn't good at all, soon they'll be forgotten because there are a ton of new artists who have been coming out with new 音楽 lately and people will become もっと見る interested in them.
Well I'm not a ファン of any of them but I would say Demi Lovato is the best her voice is very powerful Then Miley Cyrus Thhhhhheeeeeeennnnnnn......... Selena Gomez