I use a 31 inch 4K display at native resolution and it's perfectly usable and text is perfectly readable, although when all my other displays are HiDPI/Retina,

I use a 31 inch 4K display at native resolution and it's perfectly usable and text is perfectly readable, although when all my other displays are HiDPI/Retina, everything looks pretty chunky in comparison. My ideal monitor would probably be a 30 inch 8K display running at 2x scaled mode, but we're many years away from that being affordable.