Everybody always recommends their favorite camera - I've go no problem with that because you see very strong feelings about choice of format, camera operation, etc.
I'm going to advocate that you sit down and actually make a formal list of what the "perfect" medium format camera would be for you - and then look at manufacturers and model - and see what gets closest to your ideal camera.
Think about the type of work you plan on doing. Macro photography? That pretty much rules out rangefinders - so take the Mamiya 7 off the list.
Backpacking with several lenses? Ok, that pretty much points you at the Mamiya 7 for least weight, smallest size. See what I mean?
Camera that is not good for one application is perfect for another.
I have a Hasselblad specifically because it's important for me to have interchangeable backs for some work, be able to hand hold it, carry a complete kit on an airline in the overhead compartment, etc. That rules out the RB / RZ 67 for me personally.
I have a Plaubel Makina 670 because it is the smallest form factor medium format when it's collapsed making a hike with it no sweat. It also has a terrific lens, and maybe the most intuitive metering system I've ever used. I also don't mind that it doesn't have interchangeable lenses as I "see" its field-of-view as being "normal" for me. Some people couldn't live with the constraint of not being able to change lenses.
Again, a personal choice and should be part of your shopping list.
Just put your shopping list together and get the camera that is the best fit for your anticipated uses. You probably can't find a camera that will be 100% for every application. I can't, that's why I own many different cameras.