I'm thinking probably Blizzard.
Blizzard, when they're making more than World of Warcraft.
Their games have their own unique feel and vibe to them, and the fun factor is off the charts to anyone other than Dvader. So, Blizzard.
Define Nintendo-est.
Consistently good or whimsical graphics or "kiddy." 
travo said:Consistently good...
This.
I was playing Diablo III, exploring a Nephalem Rift when I came up with this topic...
There are gifts awaiting Edge and Hamster, whenever they sign on again... 
It's strange to me how they share a few things in common. Blizzard always takes soooo long developing their games that when they come out, they are incredibly fun to play, but they resemble something from the last generation. They're always a step ahead, gameplay-wise and a step behind graphically!
I guess they scale back the graphics pizzazz in order to get as many people playing them as possible. They make up for it with amazing art direction, IMO. And yeah, regarding gameplay, all of their games are endlessly iterated on and polished.
This reminds me I need Overwatch to come out yesterday.
I have my own ideas already, but I was interested in hearing some of yours!