Let me make this clear. ANYONE who votes Sonic X is either just trolling or is unforgivably treacherous. Sonic is not about... whatever the heck that show is about. I guess I have to admit I've never managed to get through an entire episode. That's saying something on it's own though. I have a huge Sonic Obession. I sing the theme song to the 90's cartoon in the shower. I watched and even managed to enjoy Underground, and there's never been a sonic game, no matter how terrible, I haven't played.
Simply put, Sonic is way past cool.
"Sonic 2"is THE Sonic game. It had just enough of everything. I still hum the music. It had Spin-Dash, it had Miles, you could super-impose Knuckles if you felt the need and it had incredibly varied gameplay and level design. There are STILL routes in Sonic 2 I've never taken and I've beaten it like 500 times.
Cons to that one? I guess some of the bosses were too easy along the way although the end boss and Metropolis are quite difficult (Unless you did what little brother did and look up a Gamefaq, cheatin' little wuss) and Tails really needs to be controlled or turned off. AI Tails is only going to cost you rings in the half-pipe.