To further my thoughts a bit, the distinction I would place on OS/2 over DOS is double: 1) first class memory protection 2) full preemptive multitasking. The distinction I would place against all widely used modern desktop OSes is the lack of first class multi-user support.
Early Windows gains cooperative multi-tasking like Mac OS classic but neither fundamentally use memory protection the way later OSes normalize and that turns out to be a pretty clear dead end. I believe there are extensions for both that retrofit protection in. Both also have some add on approaches to multi-user but are not first class designs.
So, even the most robust single user system that implements full memory protection and preemptive multitasking still seems to be stuck in a valley. I.e. whatever the actual cost in terms of implementation and increase in cognitive workload for single user systems (i.e. "enter your administrative password" prompts on current macOS or Windows administrative accept dialogs) seems to be accepted by the masses.
And note that this isn't an implicit a negative judgement, for instance I find BeOS or those in your list can be absolutely fascinating. And OS/2 is lovely even today for certain niche or retrocomputing things. Just pointing out that NT made a better bet for the long term, and some of that undoubtedly related to the difference of a couple years.. keep in mind OS/2 ran on a 286, which NT completely bypassed.