Each of these cameras has a different feel, and I always urge people to go to a store or find someone who owns them and hold the camera.
What some might like in a camera, others might find appealing.
I never had a problem with loading film in an M6, and I think the quality of construction was first rate, as it should be. I didn't like the release, and I felt the camera was a bit heavy, which provided for a very stable camera. That wasn't surprising, given the materials that are used. I felt the release point for the shutter button was too deep, so I bought a so-called soft release.
By contrast, I liked the Bessa-R and its light weight, but I didn't like the prolific use of plastic and the fact that the camera was unbalanced when it hung from my neck. The camera wanted to hang lens up, which was annoying because walking around with the camera forced me to always have one hand on it.
I've found the Zeiss Ikon to be an excellent camera ... for me. It's well built. The choice of materials is very good. It's a nicely balanced camera (no need to keep one hand on it). Not too heavy and not too light. I like the feel of the shutter release, although I wish it offered at least two manual speeds if the batteries die. For me, it's the Goldilocks of cameras.
But again, what each of us want in a camera is very individualistic. You can't beat a hands-on evaluation.
Bob, you still shooting the Bronica RF?