Last week I finally upgraded my home setup to two 27" 2560×1440 displays which are 16:9. I had two 1920×1080 before that, while at work I have two 1920×1200 (16:10), not that I've seen those in a year. I'm only a week in, but I have to say it's a really nice setup.
The increase in vertical space is exactly what I was missing while coding: that alone is a significant and worthwhile upgrade, and for that the fact it's 16:9 is kind of irrelevant. Because it's 16:9, YouTube, games, etc still work the way they always did.
Compared to my monitors at work (1920×1200 / 16:10), the benefit is I can run two browser windows side-by-side with a comfortable 1280px width that most sites work great with. 1920px is too narrow to run 50%/50%, but I find also usually wasted at 100% width.
There's not that many other options.
I can't actually find many 16:10 on the market.
4K is usually 3840x2160, which is 16:9. For me this doesn't make sense: either the monitor(s) end up being too massive, the text is too tiny, or I have to scale up and basically have the same vertical space as 1080p 16:9 just with sharper text.
21:9 3440x1440 is probably the next most popular aspect ratio, but two are just way too big for my desk space and I didn't think I'd be happy with one (it's only a tiny bit more area vs 2x 1080p).
The 32:9 "ultra-wide" 5120x1440 look pretty great, but in practice seem to have some challenges. As an example, you can't really do full screen sharing anymore because no one else can see it. Window management becomes a constant pain because "full screen" most apps/websites are just not going to be useful at 5120px wide. And for games it seems to be mixed: when they work it looks pretty cool, but many don't work properly. And on top of that, going fullscreen gaming means you don't get a second monitor to keep an eye on something else, even if your game is running in 16:9 with black bars. For video editors or people working on stupidly big spreadsheets it might make sense, but not for me. (Doesn't help it's 4x the cost of a 2560×1440 display, either).