for enjoying the view and productivity, higher resolution is prefered
but for e-sport play, especially games like CSGO, the lower the better, as higher resolution makes everything smaller
it's up to your preference and needs
component that are required are obviously a GPU meant for the resolution, and adequate system to make sure no bottleneck occurs
roughly it's like this... i think:
1050ti and any equivalent rival GPU below = med 1080p@60 and high any resolution below
1060 and their equivalent rival GPU = high 1080p@60
1070 and their equivalent rival GPU = ultra 1080p@60 / 1080p@144 / 1440p@60
1080 and their equivalent rival GPU = ultra 1440p@60 / 1440p@144
1080ti and their equivalent rival GPU = ultra 1440@144 / 4k@60
personally if i can, i would buy the 4k monitor instead, since resolution can be set on the software so even with a 4k monitor i can still use 1080p when i want to play competitive games like CSGO etc and use the 4k resolution when i want to walk around in skyrim / doing some productivity work.
however, it's all still a far-fetched dream
as even now, i still playing on 1366x768, with a borrowed monitor no less