Which one of these girls is a better singer?

I'm not really sure why but in this music video Bella doesn't really
look like she's singing...

http://www.youtube.com/watch?v=PPNMGYOm1aM

Who's a better singer Bella or Zendaya?
Who's a better singer Selena Gomez or Miley Cyrus?

Or just tell me your favorite singer if you think Disney singers are
really stupid...