I math'd this out recently and decided that ~16:9 actually would be the ideal ratio for me.. On a ~42" 8k monitor, using 2x scaling.
I'm optimizing mainly for viewing three documents side by side here. Having your primary document (e.g. text editor or IDE) centered means you're not constantly turning your head one way or another. And it has the added benefit of working well for media (compared to 3 monitors in vertical orientation). At 8k and that screen size.. the aspect ratio doesn't matter as long as there's enough vertical pixels and inches.
I found the same thing when 4k was first coming out on an inexpensive hisense TV. It would be hard to go back to only 2 or 3 side-by-side editing panes.
I'm optimizing mainly for viewing three documents side by side here. Having your primary document (e.g. text editor or IDE) centered means you're not constantly turning your head one way or another. And it has the added benefit of working well for media (compared to 3 monitors in vertical orientation). At 8k and that screen size.. the aspect ratio doesn't matter as long as there's enough vertical pixels and inches.