I don't know. Mario/Kirby/Pokémon/Star Fox/F-Zero/Animal Forest are like neck and neck.
okay dude, calling it animal forrest is just being completely elitist. It is officially called the Animal Crossing series now, by nintendo, the developers and the fan base, progress.
Anyways it is definitely a favourite of mine, but Zelda and/or smash bros are the only titles that could maybe beat it.
stuff like Kirby, starfox, metroid, etc, are beneath the tyrant of pokemon, zelda and smash, but that does not mean they are miles behind. Nintendo is the only company that can survive on IP's and first party games alone.
Lucina, Newtwo, Ridley, Bowser Jr, Little Mac, and Lloyd Irving for SSB4 Dream Roster: http://www.imageshack.com/scaled/large/577/lghv.png