The “goy” may be the most popular singer, since there are way more goyim than yidden, therefore, more people will have heard a goyish singer than a Jewish singer. However, that doesn’t mean he is a better singer, just that he is a better known singer in the world at large. Famous Mark Twain quote: (Jewish) “contributions to the world’s list of great names in literature, science, art, music, finance, medicine, and abstruse learning are also away out of proportion to the weakness of his numbers.”
Chances are good that if judged by merit, a Jewish singer comes out on top.