When comparing Tails vs BlackArch, the Slant community recommends Tails for most people. In the question“What is the most secure Linux distro?” Tails is ranked 3rd while BlackArch is ranked 9th.
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 Live session
You can run the OS from a LiveUSB.
Pro Better than ArchStrike
Contains many more tools than ArchStrike and far easier installation than ArchStrike
Pro Large repositort
The repository contains 1814 tools.
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.