As someone who's largely stuck with middle of the road hardware for financial reasons, i find that 1080p monitors are the sweet spot between having the screen estate for my programs and plenty of text on the screen, but also graphics performance if i ever want to do something else - from watching movies, doing 3D modelling or 3D printing, to gaming without resolution scaling.

Of course, i splurged a little bit on an RX 570, so currently i have multiple monitors connected to my PC, two stacked vertically, one on my PC case to the side, and another turned in portrait orientation to the other side. Personally, that setup works for me, since the way OSes do window snapping and tiling is inconsistent, so it's easy to work in both Windows and Linux with multiple monitors, without trying to split everything up into smaller zones or trying to use a tiling window manager.

However, if you want to customize things further (e.g. Windows doesn't really do vertically stacked snapping zones), the PowerToys FancyZones is suitable for this, whereas at least some Linux desktops can probably be customized to do this too (without spending too much time, i think LXDE didn't let you alter it that much, or another DE/WM, though my memory might fail me here).

There's something immensely useful about having one monitor for previewing the webpage or software that i'm working on, one for writing the code or using my Git client of choice, and another for anything from documentation, chat apps in the background or even just watching a video.

I'd say that the biggest problem with this setup is that i needed to make my own VESA mounts and a stand out of some PVC tubing and PLA plastic (3D printed and screwed on with bolts), since the options for any sort of custom monitor configuration out there are limited, if you don't want to spend a lot of money on it.