None of them are really as powerful as we think, tho they still are a lot.
latest examples were Gaga and Rihanna who prior to ARTPOP were both called "The biggest artists in the world" and then suddenly Gaga underperformed, Miley came out of nowhere overshadowed her and Katy, Beyonce became the Queen and then Taylor Snatched while Rih underperformed too
It can't be rihanna since her singles sans this tragic era have done quite well
It can't be gaga since her first 3 albums have been monumental and she had an amazing rise, same with britney (her early days were iconic )
Can't be madonna/taylor for obvious reasons
Even katy's quick little singles have had strong success worldwide...
So out of the main pop girls, the answer is BEYONCE
But this is only success wise, quality wise its def not her
