Online and the fact that they make a certain kind of game. You pretty much know how a game will feel when its developed by Nintendo. Theyre awesome games, lots of fun to play, but if Nint was the only game developer out there there would be a lot of uhappy ppl, we need the variation that the other companies bring to the table.

Nintendo is the best at theyre genre for sure but we will never see somethign like a Bloodborne, a Mass Effect or a grand Tehft Auto comming out of Nintendo. So nintendo is the best at making "Nintendo like" games, no one else manages to come even close to making those kind of games like Nintendo but it lacks quite a bit in other genres.

oh come off it, diversity wise Nintendo is by and far the best video game software developer in the world

a Bethesday or Rockstar DOES the same type of game over and over and over

you can say that Nintendo games aim to a certain demographic, sure, but they are far and away the same. Metroid similar to Zelda? Mario similar to Pokemon? sorry but they are by far the most diverse software developer there is out there (I'm focusing on software specifically)

 also bear in mind its a lot harder to maintain consistently great games depending on the QUANTITY that you produce. a Rockstar or Bethesday, for example, are only working on main project, tops 2 or so, at a time in general.  Nintendo has tons of teams working on all kinds of stuff at the same time

  for the amount of games in different genres that Nintendo produces, they are in a huge lead as the best video game developer ever (whether we're comparing now or in the past)