Parabola GNU+Linux is one of the distros that fully respect your freedom. It doesn't include any nonfree softwares and even it doesn't allow to execute it by the Linux-libre kernel. If you are an enthusiast of free software and love the minimalistic nature of Arch GNU+Linux, you'll be definitely able to satisfy your desire to build a system by using only free softwares.
Plus, Arch users can easily switch to the Parabola just by changing repository mirror urls, adding "libre" repository, and install "your-freedom" package which is my personal favorite one of clever hacks by Parabola developers. If your hardware doesn't rely on nonfree softwares, you would be getting the just same environment of the Arch that you've been using then; it is zero cost migration to the freedom of software.
Advantages: Large amount of Free Software packages available, fully free according to the Free Software Foundation, stable, rolling release.
Disadvantages: Parabola does not offer any non-free software, so you must make sure your not dependent on that. Parabola does not have all software in their own repo's. Arch's repo's need to be enabled.
Personal experience: I've distrohopped for 3 years. Parabola stopped this habit, because it has everything I want.
Use case: I mainly use my computer for web-browsing, programming and watching video's.
Setup: I run the Awesome Window Manager with custom scripts to boost my efficiency.
I followed the recommendations of the Free Software Foundation which lists the following GNU/Linux distributions as free according to their definition of freedom: blag, Dragora, dyne:bolic, gNewSense, GuixSD, Musix, Parabola, Trisquel and Uto Ututo. I tried most of them. I even bought computers pre-installed with Trisquel from ThinkPenguin and The Ministry of Freedom (minifree.org). I was able to install the version of Parabola GNU/Linux which includes the Mate desktop. It works fine but the amount of data for the updates is very high. I estimate that there are about 100 MB to download every day with th all the packages I have installed.
I wish I were more competent to install just the Parabola base install and then just the i3 tiling window manager, emacs, w3m, lynx, surfraw, mpd, mpc, gnuplot, matplotlib, python, ...