When comparing Tails vs SliTaz, the Slant community recommends Tails for most people. In the question“What are the best Linux distributions for desktops?” Tails is ranked 25th while SliTaz is ranked 33rd.
Ranked in these QuestionsQuestion Ranking
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 One of the smallest distributions with desktop GUI
The core liveCD is only 35 megabytes. The boot-from-internet option fits on a floppy.
Pro Very fast
Pro Can add desktop effects
SliTaz has a feature called "Desktop Effects" which can add shadow or fade effects to windows.
Pro Very customizable
SliTaz is very customizable. You can programatically edit and change anything you want on how the OS looks or behaves.
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 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 You can't install it to a hard drive
Con Slow internet
Tails uses the TOR network and as a result the internet on your computer will be very slow.
Con Only GNOME desktop environment
Con Install instructions are in French
When first booting SliTaz from a USB or from a Live CD, the installation instructions are in French.
Con Not much variety as to available applications
SliTaz does not have as many applications in its repositories as the bigger distros such as Ubuntu.