I'll be surprised if Sonic is able to come out on top monetarily. Mario is just a much bigger and well known character; he is practically THE face of video games. But Sonic did set the base line of 'This is how you do a video game adaptation and succeed'. Twice. Neither are perfect movies, but they get all the important elements right. So far, Mario is doing almost all that. Jury's still out on Chris Pratt's voice; but everything else so far feels spot on for Mario's universe.
I have no doubt that this is gonna be one of the biggest movies of the holiday season, the only way this won't be is if its some sorta unseen trainwreck... and well... I can't see that happening. Nintendo is very hands on with this, and Illumination rarely has a movie that underperforms. This is Mario, in all his cartoony glory, on the big screen. Even more then Sonic, this is people's childhood's coming alive.