I never liked sonic. More of a mario guy. I like the controls better. (Meaning the physics of how your character responds to everything, not what button does what)
Then again when it comes to platformers its a bit unfair to compare anything to the classic Mario games.
I mean, to each their own, but in my opinion sonic has superior physics by a technical standpoint. That is, Sonic actually has physics and Mario does not.
Mario has flat ground environments, with a character that runs at one constant speed, and only has a certain hight of jumping capability.
Sonic has uneven hilly terrain that the player uses to build momentum. Momentum is the primary aspect of gameplay in Sonic, and that momentum allows the player to change their running reach and jump to higher places than a standard jump can reach.
Again, I’m not trying to say you can’t prefer Mario, I just think people often don’t realize how Sonic’s gameplay differs so fundamentally when they are comparing the games.