I'm actually more interested and excited about a new pokemon game, and one of the very few reasons (phoenix wright too) I still buy Nintendo consoles, but I recognize Mario more like an Icon and also much more popular. But I never bought a N console for Mario, I don't even own all main Mario games on N console I own...
Pickachu is what most people identifies with all the pokemon franchise.
So from my point of view Pk is a more videogame selling IP, but probably Mario at least in vg is bigger, pk in all else (marketing stuff)