Nintendo is Nintendo, we should probably leave them out of the discussion, they're a separate thing really. They have a completely different profile than Xbox and PlayStation, and let's face it, this thread barely even mentioned them because we all know it's about PS vs Xbox.
Here's the highest-scoring games of the 2010s on Metacritic:
https://www.metacritic.com/feature/best-videogames-of-the-decade-2010s
In the top 20, the only non-Nintendo exclusives are the Last of Us games and God of War. And then there's quite a lot of multiplatform titles, such as Portal 2, Mass Effect 2, the Red Dead Redemption games, Skyrim, Bioshock Infinite, Batman: Arkham City, Divinity: Original Sin 2. Even Minecraft is available on three different operating systems so it's sort of multiplatform. Then there are games like Undertale, Metal Gear Solid V, Overwatch, Doom 2016, Rocket League or the Witcher 3 that are out of the top 20 on this list but all have been hugely successful, critically acclaimed titles. Or From Software with the Dark Souls series and Sekiro. There are also tons of smaller gems that are multiplatform, such as Hollow Knight or the Untitled Goose Game.
I don't see evidence that games that are released for both PS and Xbox are somehow inferior, overall, to exclusives. I'm not even convinced about the percentage argument. Most of the PS4 exclusives, for example, are completely forgettable, just look at the list:
https://en.wikipedia.org/wiki/Category:PlayStation_4-only_games.