Its an opinion.Its subjective.
But if you want to be as objective as possible, its widely aceppted(as in the majority agree) that Nintendo is the best developer of first party games of the big three, by quantity and quality.
It's accepted among Nintendo fans that Nintendo makes the best games, but if you actually look at the reviews, or awards and such Nintendo is no where close to being the best.
Ok, so since you seem to swear by Metacritic, I assume you agree that Zelda OoT is the greatest game of all time?
Also, why do you only look to last gen to compare the big three and their outut/scores? Because Metacritic has a handy feature where you can easily see the average score for publishers and the amount of games they have reviewed, but I suspect you actually knew about that, but didn't bring it up/include it anywhere because it went against your narrative. For example, according to Metacritic, Nintendo has an average score of 76 from 549 game reviews, of which 314 are positive, 223 mixed, and 12 negative; the highest score from those games being a 99, and the lowest a 37. Compare that to Sony, who has an average score of 73 from 538 game reviews, of which 262 reviews are positive, 265 are mixed, and 11 are negative. The highest score from those games is a 96, and the lowest is 36. Finally, we have Microsoft, who has an average score of 74 from 367 game reviews, of which 205 are positive, 146 are mixed, and 16 are negative. The highest scored game from those are a 97, and the lowest 28. From this apparently factual and correct evidence from Metacritic, since you seem to love to use it so much of course, we can safely conclude that Nintendo makes the best games, and they also have the highest output of games.
You agree of course, right?
EDIT: Here's a link if you want to look for yourself www.metacritic.com/browse/games/company/popular