@L Gebhardt The Sony 90mm macro is weak in the corners. It is a good lens, don't get me wrong. But scanning film on high-density sensors requires crème de la crème, and the Sony is not it. The focus field is not 100% flat. To compensate you have to close down to f/8, and then you're limited by diffraction. Again, for normal photography that's nitpicking, but if you want to match and exceed a Coolscan or a Flextight, you need to feed high MTF into those high-density sensors. The same applies to the Mamiya 120 macro. I have not tried others because they're manual focus and that's a far bigger limitation that people realize.
The only sensor+lens combination that I'm aware of that can beat a 60MP full-frame sensor with the 105mm Sigma Art Macro is the 100MP GFX with Rodenstock 105/5.6 HR Digaron Macro. But that's a $6K lens which also requires a motorized focusing rail and focus stitching to achieve it's full potential, which is way too much work for that price. There could be others, but I I haven't found anything after a year of searching. Two combinations I wasn't able to locate full-sized samples is 100MP Hasselblad H with their 1:1 120mm macro, and the Phase One Cultural Heritage dedicated film scanning setup (which is $50K+ anyway AFAIK).