Sonic was pretty much the one character I was hoping to come back when Mega Man showed his face back at E3. While I didn't totally doubt he'd return, given Nintendo and SEGA being buds nowadays and SEGA and Capcom forming a friendship (the Archie comics crossover was their idea, after all), it's always nice to get a confirmation.
Now that Sonic's back, I'm a little more interested in what newcomers Nintendo has planned instead of just returning fighters.