I had a 34 inch ultrawide for a while, but eventually got tired of the low resolution. Switched to a 32 inch 4K and I'm pretty happy with it. But it's a bit slow starting up, the refresh rate maxes out at 60Hz, and sometimes I find myself wishing for more space. Partially because I'm getting old and my eyes thank me for scaling up the size of fonts and such, which cuts down on the effective area of the screen.
I've been toying with the idea of getting the Samsung CRG9, but I've no idea if it would be a good choice for primarily software development. A big upside is that it's a single monitor, which will make my M1 MBP happy.