
I was a SNES kid, but surprisingly, I enjoyed the Genesis Sonic games more than the SNES Mario games. However, since then, Sonic has definitely fallen far behind Mario.
Streets of Rage was my favorite take on the Double Dragon theme, although my favorite beat-em-up game from that era overall was Konami's Simpsons arcade game (and that game is now seriously challenged by Dragon's Crown on PS3).
ToeJam and Earl was a bit esoteric for me. Catchy music though.
My own pick for Genesis mascots, however, would be Alex and Luna from Lunar: The Silver Star. And that's taking into account that I never played the Sega CD version of that game. The PS1 version of Lunar is one of my favorite games ever. Trust me, though, if I'd thought I could have talked my mom into springing for $400 for a Genesis+Sega CD combo back in the 90s, plus the money for Lunar, I'd have been a Genesis kid instead of a SNES kid.