Honestly though, in that performance Camila was the only one who shined. The others didn't really have a chance to. I remember watching it and I hadn't seen them before, and Camila was the only one I liked.
Then I saw this one and was blown away by the others....especially Dinah and Lauren
And they continued to all get their chance to shine, especially Ally in this one
It's not only about how good a vocal is but how distinctive it is. Rihanna, for example, isn't a powerful vocalist, but her voice is very distinctive. The same thing with Camila; her voice is the most unique.