At the most basic level pixel pitch (the center-to-center distance between pixels) is perhaps the most important parameter. The other parameter is observer dist

At the most basic level pixel pitch (the center-to-center distance between pixels) is perhaps the most important parameter. The other parameter is observer distance (eyeball to pixel). Those two interplay and setup a situation where resolution is utterly wasted if the observer is farther than the perceptual limit. Think of a standard Snellen chart placed at 12 meters rather than 6. And so, the decision to go to 4K displays is inexorably connected with a specification of display size and viewer distance. Ages ago IBM introduced "Big Bertha" probably the first 4K display. It was about $20K. The problem was that IBM made the display 22 inches diagonal and, at that size and resolution, you had to be 6 to 8 inches away in order to actually make use of the resolution. There are other considerations but I think being able to actually use the resolution is key. Personally, I prefer multiple (3) 1920x1200 monitors because it allows segmentation of your workspace. For example, you can maximize a the video of a course or online class you are taking while you code on the middle monitor and have reference material on the third. I know this will not be well received on HN but I have to say it. The OSX UI has been grossly outdated as it pertains to large or multi monitor setups for a long, long time. This insistance on having menu's at the top of the monitor is rather than within the application window simply isn't sensible. I've had the experience of projecting a Mac on a 40 foot 4K theater screen. The only way I can describe the single top menu bar experience is tiring and ridiculous. Windows or a similarly setup Ubuntu systems with menu's owned by the application are a dream to use on a huge multi-screen environments. I've done just that with huge stadium-sized LED video walls mapped as multiple monitors to the OS. Nothing like hqving to move a cursor across 160 feet of screen real estate to reach the menu's to show, in no uncertain terms, that a UI is broken.