The factors that will contribute most to sharpness are: 1. a fast lens, to allow faster shutter speeds, 2. lack of a flipping mirror, to make the camera less shaky, 3. eye level vs. waist level shooting, and 4. film selection. The faster the better, to allow faster shutter speeds.
I would pretty much totally ignore the technical specs of the lenses, as they are all good, and focus more on final results. Just to make up an example, Hassy might make a "better" normal lens than the one for Mamiya 7, but the fact that the Hassy is an SLR might negate this advantage for hand-held use.
With this in mind, I would say you should start looking at cameras that are not SLRs. TLRs, Mamiya 7s, Mamiya Press, Graflex and Linhof press cameras, etc.
TLRs will have some of the fastest lenses of the lot, give you a mirror for *perfect focusing accuracy* and very good compositional accuracy, unlike a rangefinder, and give you the advantage of waist or chest level shooting, which is very stable compared to eye level shooting with the Mamiya 7, Press, etc.
This has nothing to do with why I made my above comments, but my work has a user Rolleicord IId in (75mm f/3.5 Schneider Xenar lens) that we are going to E-Bay. I think it is early 1950s vintage. It fires at all speeds, and they sound close enough to use, although the shutter cocking lever seems a bit mushy and the shutter speed and aperture control levers are stiff. I would CLA it, but it works, is a user, and will likely go for peanuts when we auction it. (I am thinking $40 or so.) If you are interested, let me know via PM and I'll send you the link when we EBay it. Would love to sell directly on APUG, but I don't personally have the authority to do that.
