I wasn't familiar with any of them other than the HZX and PTB so I went to their website. Certainly just at a glance I have no idea what those other cameras do or do not do compared to the HZX and PTB, so you're right! I always get annoyed at companies with too many options that are very similar...

Anyway, just as a reference point, I also have a Shen-Hao PTB-617. That one and the 4x5, which is an older camera I was recently given, are very nice and smooth and don't have any build-quality issues. That's just been my experience. As another small anecdote, the Deardorff cameras I have handled have been exceedingly sloppy and I have always felt them to be extraordinarily overpriced for what they are. But to be fair, they are all much older cameras now, and likely a nicer one or a well-maintained / refurbished one might be excellent. I wouldn't pay the going prices though myself.