Katy Perry's star power hasn't been put to the test yet. Let's see who will stick around after she has a flop era and how -- or if -- she will recover.
Katy Perry is void of star power, period, hence always sticking in the same lane, she knows well she's not taken seriously enough to branch out of her limited web. Rihanna is one of the biggest stars on earth
The one whose recent offering has sold more albums (let's face it, Anti isn't touching Prism ), more singles, had a higher grossing tour, played the SB (most viewed show of all time), sells more albums and singles on average, etc etc!