Hello OSTexo.

Thanks for sharing.

@You : "...Developers are typically horrible at UX. MoI is an exception to that rule...."

Oh man...you're totally right!

Just to echo what you named....

Rhino : Terrible UX

3DCoat : Not so bad IMHO. It's Paint Room with its Photoshop Centric UX is very good for me. Other Rooms (sculpring,...) could be a lot better.

NVIL : Its creator Istonia is really a good guy :) He put all his effort in adding new powerful features and in debugging activity. Very remarkable what he do constantly. NVIL is very powerful, believe me. But the UX is really not his strong suit :)
Things changed a lot when Samardac and Istonia created Rocket3F, a special version of NVIL. A great step forward compared to NVIL.

Thea Render : rather inconsistent UX but...hey...great source code, super powerful CPU+GPU "Presto" engine. On my 1080 Ti really flies!

Blender : IMHO not so bad its UX like many say. Not the best, for sure, but not so bad. Tons of panels ok, but it support shortcuts very well.

And what else ?

IMHO actually one of the best UX are of Affinity Designer and Photo, especially Photo on iPad Pro.

Also this well known web App for Poly/SDS modelling has agreat UX imho : Vectary (https://www.vectary.com/about)

Ciao!