Can I ask you to be open to what I write next? Thank you.
Neither size of the sceen nor the
number of pixels have anything to do with the pixel ratio.
32x18 handheld tetris game screen would be 16:9,
as an example.
If there were NO standards like 1080 or 1024 or 900 or 720, and if we discuss the aspect ratio
solely, then ALL of your arguments (and also some, but not all of mine) would fail to discuss the topic.
Now, there
are standards. Yes. But computers have never been too tight to standards. I can always change resolution to whichever I want in System Preferences. We all know that.
This means also, that
higher resolutions MAY be supported, maybe as an option as Dell used to do it (I dont know how it is now, we I guess are not so into Dell anymore

). I am not talking about 1080, I am talking about much higher.
If to give the ratio its independence from everything else, but the matter of ratio itself, 16:9 clearly wins from me.
We all remember those times, when TV was SD only, and we could push our monitors as high as 1900x1200 - a true independence of pixels (I hope you dont bring matters like maximum pixel density manufacturing possibilities).
It could really be a switch from 1680x1050 to 1867x1050 keeping the vertical pixels the same. From manufacturing point of view, such a screen is not produced right now (and the pixels do not round as a whole, so a different res which is 1080, would be more appropriate to mention). But it is only a theory here.
My opinion is that 1680x1050 competes with 1920x1080 and not 1600x900, when it is about a screen going wider. Why were you cutting pixels off the top and the bottom, instead of adding on the sides? Because you judge the aspect ratio not by what it is, but what manufacturers made it to be. Instead of adding pixels, they cut them. It is true, but to compare two aspect ratios, they must be given the same chance to compete. 16:10 with 1050 is like someone with performance enhancing drugs over 16:9 with 900.
Having given myself time to think about it, I think this post makes more sens than others.
Now if you can prove me wrong, you are welcome
Thank you,