When comparing Trisquel GNU/Linux vs Siduction, the Slant community recommends Siduction for most people. In the question“What are the best Debian-based Linux distributions?” Siduction is ranked 3rd while Trisquel GNU/Linux is ranked 5th. The most important reason people chose Siduction is:
Apt/Aptitude, debconf or the alternatives system.
Specs
Ranked in these QuestionsQuestion Ranking
Pros

Pro Polished look and feel
Fresh installation looks great.
Pro Reliable and working great out-of-the-box
It works on many machines. Really good.
Pro Good but not so good
There's been a lot of effort put in this project through the years, there is no question about it. It's 100% free and it's very user-friendly, but it being based on Ubuntu 16.04 isn't the best thing, as you are working with software that still is actual but the versions are not the newest.
Pro Debian based
Apt/Aptitude, debconf or the alternatives system.
Pro Updates are slow, but stable. It is based on Debian after all.
It uses Unstable per default so it is still some kind of stable since all dangerous packages are tested in experimental first.
Pro Secure Boot support
It supports secure boot which is great for LiveCDs and dual boot systems.
Cons
Con Avoid proprietary-only GPU drivers
GPUs without libre drivers are a problem (not fault of Trisquel, of course). Also Wi-Fi cards in the same vein.
Con Hardware recognition is bad compared to Ubuntu.
Siduction won't install any non-free drivers by default.
