When comparing GNU Guix vs Tails, the Slant community recommends Tails for most people. In the question“What are the best Linux distributions for desktops?” Tails is ranked 31st while GNU Guix is ranked 81st.
Ranked in these QuestionsQuestion Ranking
Pro Can setup a shell which has exactly the defined libraries available
A method which works across languages and provides a reproducible programming environment.
Pro Can always roll back to a safe state
Guix creates new profile generations for each operation. If anything goes wrong, a simple --roll-back gets you immediately back to the previous, working, generation. Because it is a purely functional package management system, generations don't affect each other, so you're back to the exact same state as before : still working.
Pro Can create independent packages
Guix pack creates packages which do not need Guix to be run.
Pro No side effects when building packages
Guix is a purely functional package management system. This means that the act of building a package does not have side effects, such as destructively updating or deleting files that may be used by other packages.
Pro Can build containers right-away, from docker to tarballs
See guix pack --help and here.
Pro Easy to add your own packages
The clean and declarative syntax makes it easy to define new packages by using an existing one as an example.
Pro Doesn't require root privileges
Normal users can install packages on a Guix-enabled system, or even run their own Guix instance if the system isn't Guix-enabled.
Pro Privacy focused
Pro Has TOR built-in
Use the Internet anonymously and circumvent censorship; all connections to the Internet are forced to go through the Tor network.
Pro Easy to use with an USB key
Con Updates take a long time
It's gotten better over time but both updating Guix itself and updating the installed packages can take a long time.
Con Cannot handle filetypes that have different semantics across different versions
While the functional approach that Guix takes is great for sandboxing binary artifacts of packages, it seriously lacks any power in handling configuration files or user data. It's difficult to upgrade and downgrade files where semantics and syntax can change between versions.
Con Not for daily use
Tails is a privacy focused Linux distro. The updates that you will receive are only for improving privacy and not for improving user experience.
Con You can't install it to a hard drive
Con Saved states are not present for security
For security reasons, saved states are not supported in Tails. Files can be stored in a separate, persistent volume which must be accessed with a root password. Personal settings (e.g. -- keyboard layout, window settings, etc.) are not saved persistently across reboots. This can be a hindrance for anyone not using English as their language, or not using a QWERTY keyboard layout.
Con Only GNOME desktop environment
Con Slow internet
Tails uses the TOR network and as a result the internet on your computer will be very slow.