Personally, I wouldn’t buy a monitor only supporting HDMI today or for the past several years, but YMMV.
If your 2019 MacBook is your primary system, what others ‘might’ ever plug into it? If the answer is none, it’s quite nice to go USB-C or Thunderbolt but it depends on your specific usage, while I’ve had much better overall performance across several systems and over time using MacBooks to DisplayPort if not TB/USB-C nowadays. Ports in general are cheap enough other than it will cost a bit more on USB-C or true Thunderbolt displays.
The eye care feature is a good one as someone noted.
Also consider panel type - if graphically inclined, or well, in general other than for gaming, look for an IPS panel over a VA/TN panel. Ironically dedicated displays haven’t quite caught up nowadays vs the various display techs in TVs(e.g. OLED and similar - let alone at sane prices, etc.), although the lines (‘computer display vs tv’) continue to blend together, and some do use a ‘tv’ as a display, but not for something that small size-wise.
The resolution issue - well, I run a 38" LG ultra-wide ‘quad HD’… which isn’t a 4K or 5K display, but does give me ~3840x1600 resolution. This was after liking, mostly, the 34" curved LG, but the vertical resolution is lacking for the work I do… I can run multiple apps side by side, and in some cases, also top to bottom for smaller apps, e.g. terminal and a task management app.
You’re not looking at larger displays, but I would not buy a ‘standard HD’ resolution screen - your retina display has a much higher DPI, and there are some games being played (sorry, forget the specifics now, so may be somewhat off), but the retina display at ‘effective’ resolution close to a ‘standard’ HD screen - will still be much clearer…and many come away ‘unimpressed’ with their ‘big, new display’ compared to retina displays as a result. This isn’t a huge issue if your focus is not on small text/font sizes or a lot of visual work (e.g. photography or video editing/creation), but can become so if you use smaller font sizes, as a non-retina display (or ‘only’ a standard HD 1920x1080p’ one…) will be less ‘crisp’ for small text, as the retina displays (or a higher resolution display scaled and not running max resolution) effectively have higher pixel density per square inch and is ‘nicer’/cleaner/crisper.
Short version - get a display higher resolution vs a cheap display. 4K/5K displays still aren’t ‘required’ for most work, but you might want to see what’s available out there, and possibly upgrade in size and/or resolution a bit.
I’m biased badly, as I haven’t owned nor would I buy a 22" display in over a decade - I simply spend too much time working on the computer, from code to presentations, etc., and ditched the ‘dual 27" + laptop’ setup in favor of a properly sized ultra wide curved display + laptop screen + airplay iPad pro…and I would still consider a 4K/5K type display if I were convinced I’d get more usable real estate and it would fit on my desk.
When I was buying other displays (really limited selection of widescreens >= 1600 vertical resolution unfortunately, pretty much Dell or LG right now), I really liked Viewsonic(gave my last one to my wife as her external display), and BenQ, but I had my last BenQ lose it’s DisplayPort within a week and exchanged it ultimately for a Viewsonic.
The rest - a lot of them all use a very few manufacturers panels - but Dell, LG, Samsung, ASUS, ViewSonic, BenQ - all are pretty solid overall.
Consider IPS vs TN (get IPS panel IMO - better color in general), reasonable color gamut coverage, and go bigger than you think you ‘need’ and preferably higher than standard 1920x1080p and you should be happy. Unless gaming, don’t worry about 120Hz vs 60Hz refresh, or the various AMD and NVidea sync support for productivity, but do consider resolution and ports to connect to.
Forget about anything, especially lower sizes and price points with ‘speakers’ built-in - they’re crap in general. If considering plugging in multiple different systems to it at times, consider if the control scheme is sane, e.g. quick to toggle between input 1 and 2.
As you’re connecting a MBP, check reviews or complaints if the mac can wake it properly when coming out of sleep, as some displays are still not ‘quite’ mac-compatible (including Dell, surprisingly, as while I dislike their servers and most laptops, they do make a solid set of displays…), but again, using DisplayPort or USB-C or Thunderbolt…helps vs HDMI/Mac weirdness in many cases.
Oh, someone else mentioned this, but seriously - find a display with height and tilt adjustment to make your work environment sane and reasonably ergonomic, and at that side of display, being relatively smaller, consider if you’d ever benefit from being able to rotate it into portrait mode (longer vertically than horizontally) which is awesome for working on any type of long/tall work, from coding to documents, etc.
There’s probably more but it’s late and I’m wiped out, so that’s it from me… 
