Beyoncé is music royalty in this industry (Queen B). She's in a lane of her own, she's on another planet from every other pop girl, pop star, just everyone else #Elite. Even had Madonna calling her The Queen, watching B live.
Taylor Swift, she tops ever list at number 1 for females, tell me another female to avg 2.5 million dollars per show, sell 28k tickets per show, sell 1.5 million album in 1 week. she does not have to be great in rest of the world when you own north america the way she does, she does more in north america then most females can do in the hole world. BTW north america is part of the world.
Miley's bigger than all of them currently, but I voted for Katy. She's the most successful WW of the choices taking current album and single sales into account.
Pink is only big in 3 continents (North America, Europe and Oceania). She literally has no receipts outside these continents and she never tours outside them either.
Beyoncé, she prove it with BEYONCÉ and The Mrs. Carter Tour, she lost on the singles field, but who cares when you're an album seller and a touring force.
We're talking about the biggest POPSTAR, not the biggest RnB singer. Beyonce is the bigger singer/performer at the moment but Rihanna's influence on popular culture is way more relevant.