There are many developers in the industry who are known for producing master class games in one specific genre. The question is, who exactly is the most specialized out of this group? Below I've listed several examples, but feel free to list your own!

Nintendo - Platformers

**replace Yoshi's Woolly World with Super Mario Galaxy**

From Software - Action RPGs

Atlus - RPGs

Platinum Games - Action Hack & Slash

Naughty Dog - Action/Adventure TPS

From that list you provided I'd be inclined to say From Software.

I say Nintendo considering how highly rated and how amazing the Mario Galaxy games are

My personal opinion would probably be someone like Harmonix though. Literally all they've made are rhythm games and they don't have much in the way of other devs in the genre. They ARE music rhythm gaming lol.

From software. They are a one trick pony, but they are damn good at what they make.
U can add rockstar to the list

Naughty Dog is Platformers. They've only made two game, to my recollection, that aren't platformers, and those are kart racers.

Did you just call Uncharted 1,2,3,4 and The Last of Us Platformers? They've completely changed what the made from Platformers to Action Adventure so I don't think you should call them Platformer genre developers.

Uncharted and TLOU are certainly not platformers. If I had asked this in the late 90s, I think they would've qualified for that but they haven't made platformers in years.

Just checking, are the images showing up for you guys?

Platinum Games - cheese*