EPD and Retro Studios

Monolith Soft, not only releasing their own games, they still have time to help Nintendo a lot for lending Nin a hand to make other Nintendo games including Mario Kart, Splatoon, Zelda BoTW...

God Tier: Nintendo EPD, Monolithsoft - especially when they co-develop games like Breath of the Wild.
Good Tier: 1-Up Studios, Grezzo - They usually remake and co-develop games, they typically do a great job: 1-up is the successor to the Earthbound team.
Junk Tier: NDCube, Nintendo Software Technology, Retro Studio - I can live without these studios.

Monolith > Retro

Monolith at least can release games

EPD

EPD is a given, but i'd like to highlight Monolith.

EPD obviously, I mean if you look at EPD/EAD’s track record, not exactly a contest.

Not even close, it's EPD. Not only are they graphical wizards, the games they make are well made. Close 2nd for me is Monolith Soft though.

I don't think Nintendo actually own Grezzo or NDCube

I don't really think there's any answer other than EPD tbh ...

Question should be other than EPD, is just not even close.

next would be Retro for me, just for the fact that all their games are of really high quality, Monolith is just frustrating because of this anomaly of every new Xenoblade game being more unpolished gameplay wise than the last.