Yeah I bought a ultra wide and make it work with Fancy Zones on Windows Power Toys but dual 16:10 is still the best because it plays nice with the OS by default. I think default window management still has along way to go to suit all the different options out there.

The dual 16:10 you get two "prime" windows in the center and 2 aux windows out wide. where as with a 34" 1200p ultra wide you get 2 prime left and right or 1 prime and 2 aux with Fancy Zones, or 3 "aux". If you consistently find yourself needing 3 or 4 full size windows then the ultra wide is not ideal unfortunately.

The large 4k is just miserable because there's no ideal natural prime window location like I top posted further down.