When comparing BlackArch vs MX Linux, the Slant community recommends MX Linux for most people. In the question“What are the best Linux distributions for misanthropes?” MX Linux is ranked 3rd while BlackArch is ranked 37th.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Large repository
As of Feb. 26th, 2020 there are 2460 tools in the repository.
Pro Better than ArchStrike
Contains many more tools than ArchStrike and far easier installation than ArchStrike
Pro Live session
You can run the OS from a LiveUSB.
Pro Arch-based
BlackArch is just normal Arch with tons of tools preinstalled
Pro Suitable for professionals
Pro Easy to use
Pro Supports non-free drivers
Pro MX Snapshot: lets you make your own distro
Can create your own ISO (snapshot) and use it either as live-session and install back when needed.
With the (pre-installed) Snapshot tool you can easily create an ISO of your running system and then save it to a USB (or other media) and use "your own" distro as a live session or install back whenever you like (even on a different PC with different specs with no issues). You can even give that customized ISO to friends (selecting "non-personal" ISO when creating the snapshot; thus resetting the accounts & passwords and Home folder etc.).
Also you can save that ISO directly encrypted via MX Live USB Maker tool. Again, you can install MX encrypted during installation with just ticking a box, no matter if it's the official ISO or your snapshot.
Pro Good MX Tools and Package Installer
MX Linux comes with its own set of tools called MX Tools, designed to make life easier for users.
Pro Easy install
Pro Based on Debian
It is based on Debian and not based on Ubuntu.
Pro Lightweight
Pro Very stable
Pro No systemd
Pro Can also be used as an emergency tool
It has almost all tools to repair non booting systems or recover files & folders and save them on a safe place. And when thought together with it starts quick on live-session. In addition, you can do these with "your own", customized distro (snapshot).
Pro Live-Session boots fastest after Puppy
After Puppy Linux (which's aimed to run from RAM and which is smaller in size) the second fastest (head & shoulders) booting one (together with the sister project antiX) and also has the option "toram" to run from RAM. Yes, not only when compared to full distros, even far faster than small sized or tiny distros, especially when booted to "live-session", about 2 - 2.5 times faster on an old single core laptop.
Cons
Con Not beginner-friendly
Not great for newbies.
Con Only one Desktop Environment
Con Its XFCE version is too laggy
XFCE is meant to be lightweight, and it's almost true for other XFCE distros but not for MX Linux.
Con Old software
Many software applications are older.
Con Remixed Debian testing
It's mainly a Debian stable with some recompiled/backported Debian testing packages.
Con Includes non-free drivers
Con More than 50 tweaking softwares pre-installed
Con Longer boot time
Con 10s of media players preinstalled
Con Too much preinstalled applications
Con Causes overheating on some hardwares
Other debian based XFCE distros- Xubuntu, Debian XFCE, Devuan leave small footprint on system whereas MXLinux uses too much CPU resources on same system.
Con Installer and configuration tools are different
Installer and configuration tools are different and can take some time getting used to.