Mario has proven the better character and series. In addition to the "main" Super Mario games, his cast of characters has invented whole new genres like Super Mario Kart, Mario Party, and even Super Smash Bros.

It's too bad Sega gave up on Alex Kidd, he could have been something similar, even after the advent of Sonic. Kid Chameleon could have been an Alex Kidd game. Alex Kidd would have made more sense for most of the adventure parts of the Sonic Adventure games.