Most games are optimised to run at fixed frame rates for optimal performance when in 4K so really there is no difference between the two most of the time unless you’ve spent £3k+ on a rig for 4K60 out of all of your games.
Yeh for sure if you had to choose one or the other, it would be a PS4 for sure. But over PC I still choose an Xbone for ease of use.
Controller is subjective and Forza is fun. I played Horizon 3 but Horizon 4 I'll get on pc. It doesn't make sense to buy an Xbox anymore, I think Microsoft has realised too.
Controller is far superior, and it has Forza games. PC is far too expensive and not everyone's household allows for both a gaming setup and a "semi professional" setup.