Didn't God of War just win overall GOTY against Red Dead Redemption 2?
Didn't Sony's games mostly dominate at the Game Awards last year?
Didn't Spider-Man become the biggest Playstation exclusive ever and adored by millions?
Even a Tetris and a VR game scored higher than most of Xbox's exclusives in 2018.
But apparently Sony's first party just isn't rated that highly in real life?
It's practically the reason they're going into next gen so healthy.
Why are you listing a bunch of critical awards and conflating that with what is generally popular? Your argument is unconvicing here because your argument is "Sony impressed critics, so therefore their games are going to be generally more popular than Xbox games that don't have the same critical fanfare."
We know that this isn't true! There are numerous games - on mobile, in EA and 2K's sim sports catalogues, etc. - that don't get critical love from that niche of insiders, but that are well-beloved in a popular sense.
So if you can make this argument without having to point to a small niche of a wide audience, I'm glad to change my mind. This thinking is basically the sort of thinking that I also get trapped in sometimes, which is "the critics/the hardcores really love this or hate this, so that must be the wider assessment of the game." But nah, a simple view of the facts kills this argument.
Getting FH4 on Switch would mean as much as getting - I don't know, pick a 90+ Sony first-party exclusive. So would getting Halo, probably.
EDIT: The one part of your argument that holds up for me is the sales numbers for Spider-Man. That's a better argument, I think, but Microsoft has IPs that have sold extremely well also. I'm not here to say that Sony's first-party isn't actually good. Lots of it is! I'm here to say that the idea that Microsoft doesn't have any IP that would be wanted at around the same level as Sony IP is just untrue.