When comparing Nix os vs Devuan GNU+Linux, the Slant community recommends Devuan GNU+Linux for most people. In the question“What is the most secure Linux distro?” Devuan GNU+Linux is ranked 5th while Nix os is ranked 16th. The most important reason people chose Devuan GNU+Linux is:
It is stable like Debian.
Specs
Ranked in these QuestionsQuestion Ranking
Pros

Pro Great for Haskell development
It has all of hackage in it's package manager (which is confusingly named "nix" as well) due to being based around hashing and allowing you to compile in a sort of virtual machine (really just changing the PATH variable temporarily) it solves many of the versioning problems that you commonly have with cabal. Here's a tutorial (there's many others as well) http://www.cse.chalmers.se/~bernardy/nix.html.
Also I should note that you can use the package manager a la carte on Mac and most any linux distro.
Pro Upgrading the system is extremely reliable
Since NixOS stores all its packages in isolation from each other in /nix/store
and because of the declarative configuration model, upgrading NoxOS systems is extremely reliable. Furthermore, it gives you the ability to roll back upgrades.

Pro Extremely reproducible state of installation
Every package in your system is generated from a configuration file. This makes it very easy to reproduce that environment. Just copy the config file into a new machine and it's done.
Pro Versatile snapshot system
You can use and test snapshots without rebooting. Booting into snapshots or test configurations is possible without risking the system's stability.

Pro Has docker like system built in
Pro Allows parallel configurations for multiple projects
As everything is isolated, you can have on the same machine multiple configurations to meet project requirements that would be mutually exclusive on other OSes.
Pro Stability
It is stable like Debian.
Pro It's Debian
Devuan is Debian just without systemd, it just mirrors the the Debian archive and repacks packages that have hard dependencies on systemd.
Pro Excellent for normal people
It is easy to use and is a good choice for beginners.
Pro No Systemd
Pro Most decent look amongst other XFCE distros
Default XFCE theme is unique of all the XFCE distos including MXLinux, Xubuntu etc.
Cons

Con The configuration language is hard to figure out
For good reason. It's a purely functional language. However not even close to bash.
Con Difficult to install on non-free hardware
Unlike Debian, Devuan offers no unfree netinstall media, so if your system needs unfree drivers (e.g a laptop or a tablet), you'll have to download the Debian firmware on a separate USB.
Con No systemd
Con Fragmentation
Forked distributions like Devuan and Artix fragment the Linux community and hurt the original project. Debian users who do not want systemd should use Slackware or BSD instead.
