Well, this guy made the test. He tested a lot of stuff, Russian lenses, East German lenses, Canon, Nikkor, Helios, Iberit, Minolta, Zeiss, Leika, all the ancient shit. He used them on a Fuji X-Pro2. The videos are in German. But the conclusions are
-very old lenses are often mechanicaly (even with the correct adapter) not suitable for modern cameras with mirror (he recommends generally a mirrorless camera if you want to use old lenses). You can damage the mirror mechanism with an old lens.
-old wide angle lenses calculated for film are generally shitty used on modern digital cameras, especially at the corners, there are only a few exceptions
-old zoom lenses perform relatively good
-old Carl-Zeiss is generally shitty
-Canon/Nikkor are mediocre, Minolta performs very good (in general)
-there a some surprises, for example manufacturers like 'Revue', which produced only low and mid end lenses back in the days. They have some lenses working very well on digital cams.
-never combine speed boosters with old lenses, reduces image quality drastically in most cases
-always keep this in mind: a very good lens calculated for film does not mean this lens is very good on a digital camera
https://www.youtube.com/watch?v=13xCRXT0Acghttps://www.youtube.com/watch?v=OlXp4FYnzpAhttps://www.youtube.com/watch?v=EdCsz_2qzSo 
