If you want top notch optics I would suggest the Fuji GF670 and GF670W over the Plaubel duo. More modern design, great build and optics that are hard to beat. But it would be awfully expensive!
The clear advantage of the Mamiya 7 is the exchangeable lenses. But like mentioned above, the Mamiya 6 is even better in terms of compactness and no need for the external VF. Of course that is only relevant if you are okay with 6x6...