The problem with Sonic is he’s a one-trick pony. The point of Sonic games is to run fast. Complete the level as quickly as possible by running as fast as possible without stopping and without hitting anything. Collecting rings in Sonic is pointless because he loses all of them as soon as he gets hit.

Mario on the other hand, is more versatile. With his power-ups, jumping techniques, and usefulness of collecting coins (et al.), there’s more going on in a Mario game. And especially, with all of this, Mario translates much better to 3D than Sonic does. Sonic’s penchant for running fast doesn’t translate well to an environment that isn’t on rails; while to say open-world Mario games are fun is an understatement to say the least.