There was a time when some people thought Katy and Gaga are the same person. They started out at the same time, accomplished a lot during such short amount of time. One is compared to Madonna, the other to Michael Jackson. I think the right answer is Katy. Rihanna is an icon already, by the age of 30 she will be the legend with the most record sales ever (probably). Beyonce belongs to the Britney/Pink...etc crowd, even tho she isn't as big as the others. But I feel Gaga is pretty much done, her next era will under perform and the era after that will flop hard. I don't see Katy stopping anytime soon, she is a smart girl. So, in the end, Gaga can kill her career if she continues like this, but I'm sure she will remain a touring force (in the next couple of years at least).
I can agree if you say Judas + MTN flopped but if your saying the whole album flopped than your delusional !
Born this way sold 7M WW so if you think thats a flop than your faves album is actually paid with dust ! Let me know when your fave reaches 7M WW on her "flop" album ! & No one is Gaga's Threat !