I have a 40" 4k curved monitor at home (AOC C4008VU8, ~$1000 CAD, off-brand version of the Phillips one), and a pair of 24" monitors at work that I use in portr

I have a 40" 4k curved monitor at home (AOC C4008VU8, ~$1000 CAD, off-brand version of the Phillips one), and a pair of 24" monitors at work that I use in portrait mode. xmonad (tiling window manager) in both environments. No question the single monitor is better, and at these sizes you need the curvature, otherwise text at the periphery gets hard to read. With multiple smaller screens you inevitably get locked into a workflow where the code goes on one screen and browser/terminal/etc. on the others. With a single screen... well it's probably the same overall workflow but you can set up that partition wherever you need it. So dedicate more space to the "main" activity, and less to the other things. I'm really looking forward to 8k becoming mainstream; 4k on such a large screen just gives you the same kind of pixel pitch that you get on a ~20" 1080p monitor: "normal" but not "retina".