I would choose the AXBB-E (I already have a couple of these but they are not used with Mach3).
You should bear in mind that Mach3 is now obsolescent and no longer supported so if there are any minor issues with the CNC Drive Mach3 plugin it is unlikely to ever be fixed.
I have another UC400ETH which is a 2 Port device and this is occasionally used with Mach4.
Overall I am very impressed by the performance of the CNC Drive controllers and their back-up support.
Tweakie.