I think you should ignore the cheap Chinese controllers (which have no customer support) and choose one of the EU or USA manufactured products such as the Warp9 ESS or the CNC Drive UC300E or the Pokeys 57CNC, etc.
Please bear in mind that Mach3 in now obsolescent and no longer supported having been superceeded by Mach4.
The motion controllers I have mentioned will operate with Mach3 also operate with Mach4 if you ever need to change at some time in the future.
I use (on different machines) the ESS, 57CNC and UC400ETH controllers, each have their own merrits but they all support slave axis operation with Mach3 (and Mach4).
Perhaps check out the websites of the controllers I have mentioned and also browse the forum a little before making any decision.
Tweakie.