The Wemacro has less backlash and theoretically goes down to 1um.
Since you don't care about the controller, I'll make things brief:
-Wemacro has a very primitive controller, but offers a nice phone application, controllable via bluetooth.
-Stackshot has a great controller, I'm using the 3x, touch screen is indispensable. Lots and lots of settings to fiddle with.
-Bot controllable via computer, haven't tried, no comment.
The stackshot theoretically goes down to 2um, but it does 1um just fine. It also offers a high precision mode at the expense of a torturous high pitch squeak. If your ears are sensible to these sounds like mine, then be aware, it's irritating. I also use optic fibre halogen illuminators, the (much more pleasing) buzzing fan covers the squeak somewhat.
The major reason why I let go the Wemacro is controllability. The stackshot allows me to change the position a lot faster than the wemacro. I sometimes do deep stacks, this feature is much welcomed. I did think about adapting the wemacro to my stackshot controller, but meh, not really necessary.
A problem with the stackshot is accessories. Every one and single of their addons are just unreasonably expensive. A shutter cable is even really expensive. I got the 3x package just to not buy their one-purpose shutter cable. The 3x accepts 35mm type cables, something very cheap from China.
The arca-swiss platform add-on is also very expensive, I purchased one made by Hejnar Photo, great quality. His arca-swiss clamps are made better than the RRS ones, at a cheaper price. The wemacro does accept clamps... but one would have the clamp hanging off the platform, doesn't make me confident. Of course, a DIY platform will do the trick.
Yeah... have fun getting the optical axis completely in-line with the specimen setup. I suggest making an adapter.
The Wemacro does offer a lot more mounting options if you use an optical breadboard.
My vertical setup has the stackshot connected via arca-swiss clamps.
(I can't seem to figure out how to resize images! number x number doesn't work, width="" height="" also doesn't work, sorry for the big photos.
But yeah, I agree with the other posters. An industrial rail is the way to go if you want no compromise. The advantage of both the wemacro and stackshot is ease of mounting and great customer service.