But even if you use stuff like Rock and Cena this year, the Rumble will always be a WrestleMania setup PPV. It's important and all but SummerSlam wins as it stands alone.
But isn't that part of the point because it became such a important part of setting the stage for Mania then that is why for me it overtook Slam. But since the brand extension and the winner often not actually main eventing then the rumble has become less important. I think Slam might have a edge because of it being a number of months after Mania, which is why it is often called the summer version of WM.