It's between Gaga if she can pull off a good era, and Katy if she can maintain her level of success. I'm more inclined to believe the latter won't happen.
If Beyonce goes Sasha, which I think she will, I believe she will have the most success. She'll bring back R&B to pop radio.
Madonna ****ed up with the Super Bowl. She had a chance to really make a huge start with it, and did it all wrong. Beyonce will not make that same mistake. No way in hell she will.
But it's ok, I am happy because monsters seem to have huge expectations. 
And now answer to your question, i thing Gaga will of those three!