I will add my .02. Please note, I am a monitor elitist. However, Apple has conditioned me to be this way because all of their displays are exceptional. We have been immersed in Retina display since 2010 and whenever I work on an inferior display I rage internally.
I liken a display purchase to buying a mattress. On average, modern humans spend 1/3 of our life sleeping (buy a good mattress), a 1/3 of our time looking at a screen (buy a good display), and a 1/3 of our life doing... well hopefully doing good.
As Apple device users, we are blessed with exceptional built-in displays that are crisp, bright, and color accurate. Apple has been using Retina capable displays for years and this has saved a lot of eyes, heads, necks, and backs from excess strain.
This begs the question, why would you buy an inferior external display that turns your text into a Rorschach test and your images into mud?
All 4k displays are not the same. You want to focus on pixels per inch (PPI). And yes, this is turning into a math lesson.
All Apple devices/monitors rated as Retina deliver a PPI of 220 or higher. This is the benchmark for any display to ensure consistent clarity across devices. pWidth is the pixel width of the display. pHeight is the pixel height of the display. pDiagonal is the diagonal length of the display in inches.
Check the specs of the displays you are evaluating. Run the math. Figure out your PPI.
For example, an LG UltraFine UHD 27-Inch 4K has a pWidth of 3840 and a pHeight of 2160. The pDiagonal is listed as 27". Plugging these values into the formula results in a PPI of 163. To contrast this, looking at the LG UltraFine 5K 27", it has a width of 5120 and a pHeight of 2880. Running these numbers through the equation results in a PPI of 218.
Quality is not cheap. However, investing in a quality display is an investment in yourself. You will thank me every minute of your work day that you don’t have eye strain or a headache.
Hope this is helpful.