I do most of my work on a laptop, usually docked at my desk with two monitors. They’re actually wired into a KVM switch for easy access to my desktop and Raspberry Pi. Within the next couple years I may upgrade to a single 4k display, but for now two 1080x1920s work well.

I am running:

 +--desktop pc ----(display port) ----+
 |                                    |
 + --usb switch --keyboard/mouse      +--Dell UltraSharp 34U3415W  WQHD (3440x1440)
 |                                    |
 +--laptop ----(hdmi) ----------------+

maybe when this hits mass market …

https://c.slashgear.com/wp-content/uploads/2017/01/razer_project_valerie_ces2017_00.jpg

Using my laptop, 15" 3840x2160 @ 125% Windows 10 using http://windows10_dpi_blurry_fix.xpexplorer.com/

Hopefully once I move I’ll get one of the 40-43" 4K monitors - then should be able to run at 100% scaling instead of 125%. I like to be able to have multiple windows visible at once. plus tail -f log files is easier when the whole line fits on one line.

Resolution is king. I had 2x Dell U3011 2560x1200 as that was the highest I could get, then swapped those for a single Dell U3415W 3440x1440. Single High Res is best for me.

Single monitor on a PC, 35" with 21:9 aspect. Works wonderfully for coding.

EDIT: Acer Predator Z35, by the way.