If you think about it, GameBoy is the best selling because they've never changed their name. It's GameBoy, GameBoy Color, GameBoy Advance, GameBoy SP... Where Nintendo was a little behind on releasing systems after Nintendo 64, and then they named the next system a GameCube, so it is no longer named Nintendo. Same with Sega and Xbox, and Sony and Playstation (and in comparison, Playstation is rather new).