Sega Mega Drive (Genesis in America) was Sega's most successful trip into the console market (discounting Brazil). The console was neck and neck with the Super Nintendo for almost all it's life, and was probably one of the first serious console wars released. Sonic on one side, and Mario on the other, it aimed at a more mature audience with uncensored versions of Mortal Kombat (though later games on Nintendo's system rectified this), perfect sport simulations, and generally characters aimed at older audiences such as Toe Jam and Earl, Kid Chameleon, Chakkan and - of course - Sonic.
Graphically and musically wise it wasn't as strong as the SNES, but it just was cooler in my eyes. It was black, the controllers were shaped like a weapon Batman would use, and just the box art seemed a lot cooler.