Why even bother asking this question? this is Katy Perry's spot. And besides there is a HUGE difference between them, how can you even compare them. They both have different singing abilities and don't sing the same kind of music and one of them has been singing for decades where as the other has mostly been singing for 1 decade. No comparison. It's like comparing Justin Bieber to Eminem. So, that is why I am picking Katy Perry.