I don't think either one is a sweet spot, once software is taken into account. Most programs can only competently scale to 1x or 2x, and nothing in between. And for a 4K 31" screen, 2x is too big.
In my opinion, 31 inches, if you were at 1x DPI, is a perfect fit for 1440p. So double the pixels to make a 31" 5K screen and you're in a great spot. Text is a good readable size. Everything is extremely crisp. Compared to a 1920x1200 screen you have 20% more vertical space, and 33% more horizontal.
In my opinion, 31 inches, if you were at 1x DPI, is a perfect fit for 1440p. So double the pixels to make a 31" 5K screen and you're in a great spot. Text is a good readable size. Everything is extremely crisp. Compared to a 1920x1200 screen you have 20% more vertical space, and 33% more horizontal.