Samat :
I'd say it comes down to your personal preferences and what type of games you play. For competetive multiplayer FPS you'd definitely want to go for as much FPS as you can get, on the other hand for mostly single player you might find 4k more appealing. There's no single thruth in this, each has their own preferences and needs. And you need to find the best option for your budget.
Yeah honestly I love fps, anything lower than 60 fps seriously makes gameplay less enjoyable and i guess there are resolutions inbetween 1980 and 3840. so finding a compromise would be ideal here.
what do u think is the highest resolution say a 1060/1070/1080 can get with atleast 120fps in demanding games?