Sony first party has been better than Ninty since last gen. Sony had twice as many high rated games as nintedo on PS3 than Ninty did on Wii. that's the last complete gen we saw where both consoles sold well. Problem is you guys keep flip flopping on what constitues a better library, you switch between sales as metric on one hand and when Nintendo fails in that regard then you switch to critical acclaim. 

Nintedo games sell better because there's no competition from 3rd party software on their consoles. And when it comes to this gen I'm sure Sony first party will be have better selling AND more critically acclaimed games than nintendo. Sony Worldwide Studios only came into being last gen, so it's still relatively new but already better than Nintendo, and this gen is well on it's way to proving that for the second time critically and first time commercially as well.

According to your "Metacritic decides all" philosophy, Sony has never made a game that's as good as Zelda: Ocarina of Time, Metroid Prime, Super Mario Galaxy, Super Mario Galaxy 2, or Zelda: Breath of the Wild. Since Breath of the Wild just came out a few months ago, it's hard to see how Sony's first party can be more critically acclaimed this gen than Nintendo until they actually, you know, make a game that's more critically acclaimed than Zelda.

Also, how in the world is Sony first party going to have better selling games for this gen? If you compare it to Nintendo's eighth gen, the 3DS has a 128 million lead in first party over PS4, and even the Wii U currently has a 2 million lead. If you're just talking about the Switch vs. PS4, then the Switch has already sold 5.7 million units of first party software in its first three months. Just like the 3DS, the Switch will easily demolish the PS4 in sales of first party games. The only way to believe that Sony has a chance is to be ignorant of the data.

It's not very arguable at all. Nintendo's first party is tailored towards a niche part of the market and they absolutely love those games but the rest of the market does not.  I'm sure there's some game lists with metacore averages floating around here if you feel like saying otherwise.

Yeah because those one or two point differences really matter when Sony has twice as many 90+ rated games and 3 times as many 80+ rated games.

As for sales 3DS is neither current gen, nor a console. Handheld generations don't run in parallel to console generations so they can't be compared. Wii U has a 2 million lead with a 1 year lead on the market, but it doesn't really as 20-30% of PS4 sales are digital and not shown on VGC. Nintendo's switch games won't sell half as much as Sony's PS4 games, even if switch owners will have nothing worth buying but Nintendo games.

That's a false narrative that some have been trying very hard to push, and have succeeded to some extent, but it's far from the truth. Much like the "Nintendo has best first party" narrative.

It has been factually proven that MS takes longer to release games after their announcements, and that's not accounting for all the games they've cancelled this gen. Check link for proof:

http://www.neogaf.com/forum/showthread.php?t=1373448

Microsoft needs games that move system on the first half, Sony will have one insane line up next year with Shadow of the Colossus which will move Ps4 among core communities, specifically SoTc lovers who wanted to replay the game with insane graphics at dynamic 4K, then God of War, Yakuza 0, Spider Man and who knows what else, MHW in Japan, probably Days Gone and Detroit. 

And as I said maybe they have more planned like Dreams. 

Sure they have X this holiday to boost sales but Sony will have some aggressive price and bundles, I mean Destiny 2 bundle was just announced, cheaper than X and comes with one of the biggest games of the year.