"Quality" is really an imprecise term; it covers a lot of different things. It doesn't always have a low/high divide either. In my case what I'm looking for is sharpness, resolution and tonal range.
On sharpness, digital will usually win as it's an either/or in terms of resolution. Film will fade gradually away, whereas digital will suddenly cut out. I've observed this on photos - whereas a distant small boat will have an indistinct outline on film (I'm assuming enlargement) on digital it will either not be there at all, or will have a sharp but blocky shape. Visually, this will subjectively appear sharper, even though less detail is present. The same effect occurs with film, where shsrply resolved grain will creat a better illusion of sharpness thsn a fine grained print, other things being equal.
Resolution comes down to enlargement. Physics dictates that even a perfect lens doesn't give infinite resolution, and the more you enlarge the more you "dilute" the detail density. Our eyes require a certain amount of resolved detail to give an impression of sharpness. Yes, you can get away with less. But put two photos side by side, one with more and one with less detail, and you can tell the difference. In my case, I know what a print from medium and large format looks like, and 35mm doesn't cut it for me.
Last year, I made some A4 and A3 prints from 35mm Kodachrome slides taken using Olympus lenses on an OM1/OM2. The quality surprised me as it was better than I expected, but it still fell short of 120.
Tonal range almost comes down to tonal transitions, and again, the more you enlarge the worse it will get. Taken to extremes, the ultimate enlargement is represented by an electron microscope image of a negative, and that is just black and white. It's the newspaper dots again.
Not all photographs require these qualities; it's just that what I do requires them to satisfy me. And I'm the only person I intend to satisfy.
So the quick summary is that given the same lenses, the illusion of sharness that digital has built in would give it the advantage over 35mm - as it's a full frame camera, the degree of enlargement is the same. I haven't actually calculated how many lppm the a7r2 has based on pixel per mm, and I may do do now. But my guess is that it's higher than many films, giving another advantage over 35mm.
Hence my conclusion that unless I want to use 35mm cameras, digital is better for me.
I can't let it rest just there though. I can detect a different quality (there's that word again) in digital black and white to medium and large format black and white, at least at my print sizes which are A3 and A2; and the film images are better to my eyes. Hence my continued use of roll and cut film.
I'll apologise now for typos, as this is being painfully tapped in on a tablet.
