You should buy the Bronica if you want MF RF. It's as plain as that. Here is why:
Fuji 645 : plasticky cameras. Pocketable more than the others (except Plaubel). Light-weight. AF on some of the newer models. Cheaper - about 1/2 the cost of most other MF RFs.
Fuji 67,69 - big negs, nice lenses, heavy, big cameras, no interchangeable lenses - not a good thing. Gotta buy anothe camera if you want another lens. Not a reasonable option unless you don't mind shooting with one focal length all the time.
Plaubel Makina 67 - beautifully made, wonderful Nikon glass, FAST glass for MF RF standards at f/2.8. Well built. Simple design. Collapsible into a very flat - most pocketable of all AND big negs. Hard to find. Expensive. NO METER. That was enough for me to give it a no vote. But that is because I have no skills with eyeballing exposures.
Mamiya 6 - collapsible lens . . . not really that useful, and doesn't get as flat as the Plaubel. Cheapy feeling build. A number of annoying mechanical things that one must wrestle with : changing lenses requires operating the shutter curtain manually. Must collapse and open the camera (unless you keep it out - in which case having that collapsing function makes little sense). Not much smaller than the Mamiya 6x7 cameras - might as well get the bigger negative.
Mamiya 7 - generally thought to have the sharpest lenses in the world. 43mm wonder wide angle lens. Bigger than some, but smaller than the Fuji 67 and 69. Nice, smooth, quick focusing. Nice big negative. Nice VF - but not as nice as the Bronica - smaller focusing patch as well. EXPENSIVE. Multiple times as much as any of the others mentioned here. Buying a wide - normal - long kit would cost you upwards of $4000 . .probably closer to $5000. The Bronica . . . maybe $2000 at most. Probably about $1600. Gotta change film a whole lot more often with the Mamiya- a pain when shooting street stuff.
Bronica RF645 - built the best of all. Perfect selection of focal lengths for MF RF : 45, 65, and 100 which translates to 27, 40, and 60 in 35mm. A little wide for some, but just right if you are a street shooter or pretty much anyone but those seeking to shoot headshots and macro still life work. Low cost, considering its amazing value - $850 for the body and 65mm lens at KEH. $430 for the 45mm, cheaper on the auction site. The lenses are nearly free of distortion. The 45mm is amazingly sharp, zero vignetting at any aperture, and straight lines are straight. See my website in the street photography gallery for examples - all taken through the 45mm but three. Focusing is stiff . . . I like it, though, because it saves me from clumsy focusing. It holds focus nicely when your hands are not as nimble as they could be. Compact. SMaller footprint than my Nikon D70+50mm. Smaller than any of the Mamiyas, Fuji 67 and 69. Best metering I've ever experienced. I shot more than 500 pictures with mine so far, and have had not a single imperfect exposure. Not one. And some very tricky lighting. The 45mm is useable without the external viewfinder. . . and all three lenses are coupled - unlike the Mamiya where the superwide 43 and the long 210 are not.
One big thing. . . the Mamiya will be easier to service in the distant future, though Tamron in New York has serviced mine (funny VF noises) and they intend to stay at it for another 10 years.
