It is a matter of personal preference. Even though I have an ultrawide monitor to run MSFS, I also have a second 16:9 monitor to display other applications and pop-up windows. I like it this way so MSFS can use the full area of the main screen.
A single ultrawide monitor might not be optimal in your case since the VFR map and charts would still overlap some of the simulator window. 2 standard monitors might be best for your usage.