I bought that original 5k iMac on release day in 2014. I was thrilled with that display, and stoked to see the entire display industry go the route of true quadruple-resolution just like smartphone displays did.
Sadly, it basically never happened. There was the LG display that came out a couple of years later. It didn't have great reviews, and it was like two thirds the cost of an entire 5k iMac.
It took Apple over 7 years to release their standalone 5k display, and there are a few other true 5k displays (1440p screen real estate with quadruple-resolution, not the ultrawide 2160p displays branded as "5k") on the market now with prices just starting to drop below 1,000 USD.
Unfortunately in that time I've gotten used to the screen real estate of the ultrawide 1440p monitors (which are now ubiquitous, and hitting ridiculous sub-$300 prices). As of now, my perfect display for office work (gaming, video/photo work, or heavy media playback are different topics) would be 21:9 with 1440p screen real estate with quadruple-resolution—essentially just a wider version of that original 5k iMac display.
The iMac Pro is nearly 9 years old at this point. At the time, there was no other option for a retina-quality 27" display, but you could get a 4k 27" for $400.
A decade later, it boggles my mind that it's so hard to find a retina-class desktop monitor. The successor to the Cinema Display is basically an iMac, and priced like it. There have very recently been releases from ASUS and BenQ, but it still feels like an underserved niche, rather than standard expectation.
All that is to say: hard cosign.
You can get a 27 inch 5k from Asus for $750. A 31.5 inch 6K goes for around $1200. A 28 inch 4K is around $350-$400.
It was also really disappointing to see 24" 4k displays disappear from the market instead of becoming the new standard resolution for that size. A few years ago, there were several options including a cheap LG that was usually around $300 or less. Those all seem to be gone, likely for good, even though there are still plenty of 24" displays with 1080p and even a fair number with 1440p.
The LG UltraFine's were garbage, but got better over time as either the firmware improved or macOS added drivers that worked around the nonsense. For a while I ran with two of them on an iMac Pro with a 5K itself, but switched to a single Pro Display XDR with a laptop eventually. I'm very sad to see the 6K/32" form disappear, it's by far the best screen I've ever used.
I bought an LG Ultrafine 5k at the time and felt kind of stupid for being spending on it. But nearly 10 years later... its still my daily driver. Best ROI of any tech equipment I've bought. It changed my mind about how to think about it, not just the monitor, but having speaker / camera / mac built in, and all over one cable, its been such a joy when I bounce around the house to be able to plugin / unplug so easily; or when I swap from work to personal laptop. Its such a simple setup. Im definitely considering the Apple one, basically regardless of what it costs, once its time. Its simply been too convenient to have a one-plug solution for the laptop that has everything I need, never breaks (my LG may be exception here lol), and that has somehow taken forever to be super ceded by something better.
Only thing that holds back that thought lately is, I'm suddenly spending more and more time in multi-pane terminals, and my screen real estate needs have dropped. The only two things I greatly miss now on my laptop is keyboard quality and general comfort (monitor height, etc).