I actually prefer the Pentax 67 with the 105mm...
Jeff, I have personally owned both the Mamiya 645 1000s and the Pentax 6 x 7. The Mamiya had the 80mm, the Pentax usually wore the 165mm.
Both are superb cameras, both have superb glass. With either camera, you just can’t go wrong—so long as you get one in decent condition of course.
Ergonomics and handling for both are easy, and you can do anything you can think of with them. In the darkroom with an enlarger, the 645 images had enough grain to focus on, but wet prints under 8 x 10” could easily be mistaken for 4 x 5, with careful technique.
The Pentax was even better: if I shot Pan-X or Verichrome Pan and developed in D-23 or Morris Germain’s Fine Grain developer, you couldn’t focus on the grain in the enlarger out to 11 X 14”! You just went to a few edges in the image to find your best focus. 8 X 10 prints could pass for LF contact prints.
I regret selling both cameras long ago. With an Epson V550 today, one could be making masterpieces. With Acros or Provia, the results would be jaw-dropping!
If I could choose any MF camera right this second, it would be an RB, due to the glass, racking the entire lens unit for focus, and ergonomics. The Pentax
would be a close second, tied with the Mamiya Super 23, both because of superb lenses, the 23 getting an edge for the massive negative.
IMHO, you can’t beat Mamiya glass in MF, and I include the European products as well. The Mamiya 645 has excellent ergonomics & lenses and a great system for any phographic purpose.
The larger Pentax negative is rather better, and the camera’s ergonomics are easy to master.
An RB (or RZ if you want some automation [ugh]) will provide the finest MF negatives in 6 x 7 format possible, short of using a view camera with lens/film plane adjustments only needed for specialized commercial work. Of these choices, they have the worst handling characteristics, given their sheer size and bulk.
One final thought is the Fuji GX680, an RB on steroids, or what the child of an RB and a Graflex would look like. It makes a 6 x 8 negative and very RB-like, also with great lenses. But you could injure yourself trying to use it handheld with a neck strap...