I switched from a 40" 3840x2160 display to a 38" 3840x1600. I find the latter more comfortable for three reasons, one of which is that I don't have to move my head up and down too much.
(The other reasons are specific to those screens: the 40" wasn't curved, and had a slightly inferior screen.)
(The other reasons are specific to those screens: the 40" wasn't curved, and had a slightly inferior screen.)