I recently spent an unreasonable amount of time looking at monitors for myself and for friends. I have an IT background so I can decipher all the specs but it's still a lot of work.
- Dell U-series are for color sensitive workloads and are built to last. I've requisitioned at least 50 of these over the last 10 years and had exactly 1 failure. All the rest are going strong with 10,000+ hours on them.
- Dell S-series are office/gaming monitors. Parts are generally substandard to the U-series and are not good for design work if that's your intention (you never specified your use). Advantage: price.
- Asus Proart line (like the PA248QV you mentioned) are also for graphic work. I have one myself and find it quite nice. The 75Hz refresh rate is easy on the eyes, along with the blue-filter setting and the lack of PWM. Asus has a 32-inch 4k model coming out "soon" but it will most likely cost $2000+.
- BenQ PD-series are also great. The PD3200U and PD2700U are both good. I recommended 3 of these monitors recently and the owners are very pleased with them.
- Ultrawide monitors are just two regular monitors put together but at a cost twice that of two regular monitors. The one (and only one) exception to this is the LG 34WK95U-W. It's classified as a 5K2K monitor, as in, it's a 4k monitor but with extra pixels added, as opposed to a 4k monitor with pixels chopped off the top/bottom.
- LG makes the panels in a lot of good monitors like the Dell U-series so the 4k and 5k models for sale on the Apple site are the "it-just-works" choice.
- Everything else is mostly trash in my opinion. Asus Tuf gaming, Acer, Gigabyte, etc. You might find a diamond in the rough but unlikely.
Shopping by price is what makes monitor buying so hard, otherwise you would've just bought the Apple XDR and been done with it (the perfect choice btw). Monitor reviews are not very helpful because they're usually made by someone with a review unit for a week. You have no idea if it's going to fail in a month or have some other weird thing. Amazon reviews can help but really-- you get what you pay for with monitors. You won't find a lousy $2000 monitor and you won't find a good $200 monitor.
Decide on a size, decide on a resolution, and spend the most your budget will allow. Monitors are supposed to last at least 10 years, often 20 years. Even the Apple XDR amortizes to $300/year for the 20 year expected lifespan and I guarantee you would be thrilled with it, even at that price.