Coming as very mild criticism, this is not the first time I have seen people comparing the Mam 6/7 with the Bronica 645RF.
The Mamiya is at a distinct disadvantage in such a comparison of physical size only.
The Bronica offers a negative that is only 2.7 times the area of a 35mm, while the 6 square or 6X7 negative is more like 4 times the area of 35mm, or roughly 1.5x the area of 6X4.5.
Personally, I rank Mamiya, Bronica and Fuji lens quality somewhat the same. The Bronica 645 is not a particularly small camera, and would be better compared to a 6X4.5 camera, but that's difficult to do in 6X4.5 media
It seems to me that the closest one can get to a true apples to apples would be the Fuji GA645Zi which gives a zoom range of 55-90, approximating the use of interchangable lenses (and far more expensive for that selection in the Bronica) than the lens selection for the Bronica 645RF.
Additionally the Fuji ZI is a one camera carry.. no bag and extra lenses...Need a new focal length.... press the zoom button.
I used to shoot Bronica MF and was hard on the trail of buying a 645RF, until I saw the price and difficulty of finding the 100mm lens.
I opted for the Fuji GW 690 and later the GA645Zi, after using 3-4 of the GS645 series. I have had 3 of the GA645Zi's and never regretted the switch to Fuji. I actually believe the EBC coatings on Fuji lenses were formulated to enhance Fuji's various emulsions.
Just another look at the exercise.