Ask HN: What is the optimal monitor aspect ratio for programming?

Like many people on HN, I practically live inside a text editor, a terminal, and a web browser (to read documentation). I handle these with a tiling window manager. What are good sweet spot monitor aspect ratios and resolutions for plain text? I used a 16:9 (1366x768) 11 inch screen for long time, but I realize it is limiting as it is too short and too narrow to split into several windows. Some time ago, I switched to a 16:9 2k (2560x1440) 27 inch screen. A mainstream setup now. It has been a great increase in productivity as I can now comfortably split the screen with StumpWM or Emacs and have 2 ample windows side by side. 4k screens are typically 3840 x 2160, so still 16:9. With 1.5 scaling, that's the same as a 2k screen. Just more smooth text. If cost is not a concern, it is generally better. Unless scaling is still problematic in your platform. What about other aspect ratio-resolution combinations? I have heard great things about 21:9 3440x1400, where it is easy to fit 3 windows side by side. Sadly I haven't seen any 2k 16:10 screens (2560x1600), or 4:3 (2560x1920) which would be great for having two taller windows side by side. However, there are some intriguing 1:1 2048x2048 and 1920x1920 panels around mostly used for air traffic control. Eizo does sell one 1920x1920 for end users, and it is not too expensive.