So what is unique about MX ?

The best thing about MX is its cloning & remaster functions.

essentially, you get a nice stable (but sometimes aged (so u need backposrts)) debian jessie.

if you set it up nicely , add tons of packages asf., transferring that exact installation to other drives is just so easy and fun.

those actions in the "MX tools" GUI  are called: 

snapshot (create ISO)

minstall (full install on HDD), optionally keeps all settings from your current running install

create live ISO (write an ISO file to USB with persistence)