Get LG UltraFine or DELL UltraSharp monitors. These monitors are best choices for Mac.

Dell U2723QE gets my vote. 4K resolution, great color accuracy, and USB-C with 90W power delivery to charge your MacBook. Much better value than the Studio Display at $500. Plus, the build quality is excellent and Dell's warranty service is top-notch.

To add to the point above: everybody loves the Dell Ultrasharp or the LGs, and for good reason since they handle the USB-C basics well. But I've tried many setups over the years and there are better options if you're doing serious color work under that $800 mark. In my experience, the ASUS ProArt PA279CRV 27-inch 4K HDR Monitor is actually a better buy for design. It hits 99% DCI-P3 and has 96W power delivery. That extra wattage matters because the 16-inch MacBook is a power hog... a 60W or 90W charger can actually let your battery drain during heavy video exports if you arent careful. Heres what you should look at:

• Color matching: The BenQ PD2705U 27 inch 4K Designer Monitor has an M-book mode that matches the Mac screen colors better than most standard panels.
• PPI Scaling: 4K at 27 inches is the sweet spot. I'd stay away from 1440p monitors since macOS scaling makes the text look kinda fuzzy tbh.
• Build quality: Honestly the BenQ and ASUS stands are way more stable than the cheaper LG ones. Basically, if you want something that isnt just a standard office monitor, those two are your best bets for a pro workflow.

Honestly, I am in the exact same boat as you. I have been stressing over this exact setup for my 16-inch for weeks. Everyone keeps suggesting the usual Dells, but I am still sitting here with a dual-monitor setup that just feels off color-wise. Since you are doing photo editing, be careful with some of the cheaper 4K panels out there because the text scaling can get really weird if the pixel density isn't perfect. I would suggest you look at the BenQ PD2725U 27 inch 4K UHD, which has been on my radar lately. It handles the Mac color profiles surprisingly well, though make sure to check if you actually need the Thunderbolt 3 daisy-chaining before you drop the cash. It is a bit pricey, but for design work, the uniformity is way better than some of the entry-level UltraSharps I have tested. Just my two cents, but it is worth checking out if you want to avoid buyer's remorse.

LG 27UN850-W: https://www.amazon.com/LG-27UN850-W-DisplayHDR-Borderless-Adjustable/dp/B08CVTTNN4?t=t=5422-20

For your 16-inch MacBook Pro, consider the Dell UltraSharp U2719DX. This 27-inch monitor offers a 1440p resolution, delivering sharp visuals ideal for professional tasks. It features an IPS panel with 99% sRGB color coverage, ensuring vibrant and accurate colors. The ergonomic stand allows for tilt, swivel, and height adjustments, enhancing comfort during extended use. While it lacks USB-C connectivity and built-in speakers, its overall performance and build quality make it a solid choice for creative professionals.

Apple display.

Dell Ultrasharp 27” 4k is a good choice.

Dell U2723QE

Aim for at least 4K (3840 x 2160) for clarity, though some 5K options exist at a higher price.