There was a term with certain large format lenses that got tossed around several years back -- proponents of the special look referred to it as "plasticity." I never understood precisely what they meant, but suspect it was something visibly tangible to them that was difficult to describe verbally. (I am reminded of a famous line from the movie "Chinatown" ...
)
As for MF, I agree that it has a unique look, but more importantly, a
pleasant look. But then I think my Leica files have a pleasant look too.
I suspect the look I am referring to has to do with a combination of things, and foremost is probably the absence of an AA filter. I suggest this, because I've never seen the pleasant characteristic I'm referring come out of a camera with an AA filter. Next I suspect it has to do with the glass. Some lenses have a smoother transition from the plane of sharp focus to the oof areas of the image. I have found those lenses mounted even on a camera with an AA filter improved the "look" of the files to my eyes. Unfortunately, it never boosted it to the same look as from a non-AA camera, but at least was clearly better.
In the end, when I mount a good lens on a camera without an AA filter, I get a higher percentage of "pleasant" images...
My .02 only,