4k at 27" seems to be the sweet spot for people who aren't blind. In addition, instead of window managers get 2 or 3 smaller high resolution screens. Multi monitor is the easiest producitivity boost for programmers.

At my company everyone gets 2 monitors. We started with 19" in 2006. Moved to 24" after a fire and insurance replacement and then have upgraded to 27" primaries as sales and new machines were ordered.

After 7 years of multi monitor usage with a team of 12 people I can safely say that bigger is not always better. More desktops to work with are a boost. Pixel density is nice, but the OS by default handles multi monitor much better than any window manager and you can do things like one horizontal and one vertical.