I'm really a huge fan of Sonic. I've played the games since my childhood, beginning with the first Sonic on Megadrive of course.
I like especially classic and adventure eras, when the games had a good storyline and took time to develop the characters. The classic era on Megadrive was absolutely great with its eclectic environments and good music. I could feel the atmosphere of each stage, where the world of Mobius took shape.
Nowadays, since Shadow the Hedgehog, the games are... well, different. There is less character development and some gameplay ideas went terribly bad. Not mentioning the Dimps copies : Sonic Rush (the only one great for me, what a soundtrack!), Sonic Rush Adventure (okay, a sequel), Sonic Colors DS (okay, Sonic Rush in Sonic Colors...), Sonic the Hedgehog 4 (no, just no...).
But Sonic Colors and Sonic Generations went well at least. There is just no real story anymore...
I still consider Sonic and MLP as my two favorite universes. I'm more into MLP now, though. Sonic Boom was not as great as I expected after watching some episodes.
I think MLP and Sonic share what I like the most: interesting and well-developed characters, good music, good environments.
Sonic isn't developed anymore I think. There's even no more real games these days. (portages and mobile games aren't good at developing a story)
My favorite characters are Twilight Sparkle and Tails, they are everywhere on my computer and my room.
I even created a forum which is the first and unique French forum about Tails. This forum passed its 5th birthday last July. And we hope to continue with maybe a new era for our favorite two-tailed fox and his friends.