Following @MacSparky’s lead, I am setting up a 2nd monitor in portrait orientation next to my 27" 5K iMac. A 24-25" monitor is the best size for my space; 27" would be a bit large - see picture. The portrait-mode monitor on the right is a Dell U2419HC, (24", 1080p). The text displayed in the 1080p monitor is a little fuzzy compared to that on the iMac, so I plan to return the 1080p monitor and purchase a 1440p or 4K monitor.
First question - Is it important for the new monitor to have a USB-C connection? My iMac has Thunderbolt 2 connectors (essentially mini-DP for a monitor cable, correct?). Newer Macs have USB-C (Thunderbolt 3). I plan to purchase a new iMac in a year or two.
Second question - for a 24-25" monitor, which screen resolution would be appropriate, 4k (3840 x 2160) or “UHD” (2560 x 1440 native resolution)? There are several modern-looking (very thin bezels) 24-25" monitors with 2560 x 1440 resolution, but few 4K resolution monitors in that size that have the modern, thin-bezel look. A small-footprint stand that allows pivoting to portrait orientation is also a requirement.
The size of the 24" Dell U2419HC is perfect. Appearance with the “Infinity Edge” thin bezels is nice, and there is a USB-C connection. The native 1920X1080 resolution is not enough, however.
I found other choices in the 24-25" range that are 4k (3840 x 2160) or “UHD” (2560 x 1440 native resolution). Others have stated, and I tend to agree, that the 2560 x 1440 resolution is about right for a 24-25" monitor, considering the text size and sharpness when displayed at native resolution. If I purchased a 24" 4K monitor, I would probably prefer text to be scaled to a larger size, i.e., displayed at non-native resolution. My eye-to-monitor distance is 32".
Dell Ultra Sharp 25" (U2518D), 2560 x 1440 $267
Dell UP2516D 25.0" $345
BenQ PD2500Q 25 inch QHD 1440p $299. Manufacturer claims excellent color calibration.
Dell 24 Ultra HD 4K P2415Q $409 (4K, has thicker bezels)
Any thoughts on these choices? None of these has a USB-C connection. Is that a problem in terms of connecting to newer (or future) Mac computers which have USB-C connectors? I assume that connecting the above monitors to the newer Macs’ USB-C is simply a matter of using a USB-C (Thunderbolt 3) to DP (or mini-DP) cable. Is that correct?