27" x 1440p has been my go-to for a while now. Works well without scaling between win/mac/linux, does not dominate the desk completely, high quality monitors are readily available in this resolution etc etc.
Plus, if I take a working vacation somewhere it's a lot more practical to schlep around one 24" or 27" than an ultrawide.
Also, just as an ergonomic thing, I could angle in the two outer screens a bit while not having one of those icky curved screens.