xbox has never ruled supreme. neither has PS. nintendo did for ages, then came the big three. Family gamers want the nintendo for family friendly games, and with current systems, something that appeals to many age groups. Xbox started out as the expensive gamers console, then went the cheaper casual gamer, now back to expensive because it wants to be something there is no need for (entertainment system. please, what a joke.). Playstation was built to cater to the growing population of gamers that didnt have to money to do PC gaming, and wanted more adult games than nintendo. Then came the PS2 which was the casual gamers console, then flipped with xbox then right back.
If you want to go into units sold, between PS3, Xbox 360 and wii, well wii outsold them by a good bit. nintendo's hand helds have no equal. No game company can really claim superiority though nowadays. If one wanted to claim one is, that honor has to go to nintendo even if the wii u has not been doing that well.