What are you scanning mostly? 110, 120, 135, large format?
Personally, I’ve scanned with a Canon 80D and a Canon 5DII, and both work fine (regarding your question about crop sensor or full-frame). However, it changes a lot which lens I prefer to use. Lately, I’m loving my 100mm macro (max magnification 1:1) which works better on the full-frame for 135 film. It gives me a reasonable distance between the negs and the camera to work with. When using a crop sensor, the camera should be placed a bit farther away, which your mounting setup may or may not be able to handle.
Have a look at the possible macro lenses that you would be willing to buy, then estimate at what distance your negative would be filling your sensor. See if this distance is something comfortable. Stay away from extension tubes or close-up lenses if possible since they amplify glare which in turn makes color corrections more troublesome.
I’m assuming you are not listing the file size in bytes, but instead in mega-pixels, right? For me, 20ish Mpx is good enough, I know that some films may deserve a bit more resolution, but i’m not too much of a pixel peeper. But since all your cameras are similar in resolution I wouldn’t worry too much about this.
In terms of dynamic range, here you may see some differences between the newer and the older sensors and the FF sensor may outperform the others. This is quite important since, sometimes you may run into posterization issues. However, I’ve never used the camera’s you list, maybe some other users have some experience here.
Do not worry about dynamic range of negatives. The shots you take from them hardly fill the histogram, at least I have not had any issues in this respect so far. I usually expose 1 to 2 stops over, keeping the camera’s histogram a bit left off the right edge.
That’s one of the widest histograms I found in my collection. It shows a white balanced shot.
The left and right peaks are caused by the film holder and the unexposed part of the film respectively. Taken with an EF 100mm f/2.8 Macro USM on a Canon EOS 5D3 off a 645 Kodacolor negative.
Digitizer is right, of course: One of the jobs films are designed to do is flatten out the dynamic range of a scene so it fits within the limitations of the printing or viewing process. That means a negative is almost never going to use the full dynamic range of any of the cameras on your list. Once in a while you might get a problem negative (typically a black-and-white negative that has been both overexposed and overdeveloped, resulting in very dense highlights) but I usually handle those by capturing twice, once at an exposure tailored to the thinner areas and again at an exposure tailored to the denser areas. Then I have to blend them in post-production, but that’s really no worse than the desperate gyrations required to print the same negative in a traditional darkroom!
One thing to keep in mind in your choice of a macro lens is that if you pick a longer focal length (like all the wildlife guys are always telling everyone to do) your capture setup will have to place the camera farther from the film holder, making alignment more difficult and making the whole business more rickety. Everybody’s always telling me I’m wrong, but I prefer a normal-focal-length macro lens that lets me use a sturdier, more-compact setup.
It’s the lens I’ve had for a few years and it works nicely. It is an old design though and newer lenses can have better resolving power, which will show on high Megapixel cameras. I’m quite happy with the lens and the results I get from my 20something camera. If ever I wanted higher resolution, I’d stitch a few shots.
If you want to buy a new macro lens, verify that it can get you the scale you need. Some lenses bear “Macro” and only go to 1:2 or even less. I strongly recommend to get a lens with a tripod collar. It helps making a stable scanning setup. Check out the following posts for inspiration.