Now, I want to update to Apple's Pro Display XDR, but can't justify paying ~7 times more on it for now. Although 24-inch and 4K was a huge improvement for someone like me, used to only using a MacBook display (I spend the workday programming, and love photography), I still feel like 4K isn't enough.
I can't comfortably open my editor/browser, while also watching a video, for example. For some time I've tried to use my MacBook 15 Pro as a second display, but that didn't work either. I hate the fact that there're small differences in color/brightness, even though the quality of either individually is superb (the external is slightly better)... The only thing that helped a little bit with regards to using multiple displays was using the iPad to play videos thanks to AirPlay, but this is suboptimal.