So a more practical question then - 27" or 32" for a 4K monitor?

27" at 150% = ~109 logical DPI
32" at 125% = ~109 logical DPI
32" at 150% = ~96 logical DPI

So the 27" would be squinting for old software, comfortable for newer defaults. 32" could do either depending on scale factor, but it's biiggg