I love Sega Genesis, but if you do not care much about having the original console, just go download the "Gens" emulator along with the Roms to play on it. It's free and if you don't like it, you win, because it was free.
My favorite game on Genesis is Comix Zone. It's about a comic book writer that gets sucked into his own comic book and your goal is to work your way through the pages of the book and saved the lady in distress. There are two endings...as you go through the levels, you build points towards a "Super Hero" meter, if the meter is full at the end of the game, you get a different ending then if it wasn't full.
