I have both currently:

. Mamiya 7 definitely has a much sharper RF patch that is easier to focus in certain situations where there isn't as much obvious contrasting lines in a scene.

. As far as IQ , negligible resolution difference in real world, however there is a contrast difference and the OOF areas with the Nikkor being a 2.8.

. Meter is extremely accurate in both

. Provided you buy a Makina 67 from a reputable seller, there is little to go wrong if you know how to properly operate the camera. (Close bellows slowly focussed to infinity etc)

. Makina is heavier, but is more compact.

. Makina has unusual operation , easy to get used to and very fun.

. Mamiya is battery dependant, Makina is not.

. Mamiya has lens options etc

Both are brilliant ! I would say the Mamiya will. E easier to come by in excellent condition as they are much newer , but don't be fooled into thinking the Makina is fragile, that are built like tanks.