I've never had the Mamiya 6, but am more than happy with my 7II. Superb lenses, accurate meter, lightweight (relatively) and feels great in my hands. I did have - very briefly - a Fuji 645, which was also a terrific camera; but it had a problem creating "fat rolls", so I took it back to the dealer. Sorta wished I'd kept it though, & had the problem rectified. It also had a great feel, was easy to use, with an accurate meter. I have waaaay too many cameras right now, but the 7II will be with me if all the others are jettisoned down the road. I just really love that camera! Of course, I love my Hasselblad, and Holgas, and Yashica-Mat, and F100, and F3HP, and Leica IIIc, and ... well, you know. It has to do with wasting film. Lots of film...
Guess I'll keep 'em all...
IR