Gentoo unstable was a little bit tiring in the long run. The bleeding edge, but often I needed to downgrade because the rest of the libraries were not ready

Gentoo stable was really great. Back then pulseaudio was quite buggy. Having a system where I could tell all applications and libraries to not even link to it (so no need to have it installed at all) made avoiding its problems really easy
But when my hardware got older and compilation of libreoffice started to take 4h, I remembered how nice it was on Slackware where you just install package you broke and you're done

Arch looked like a nice middle-ground. Most of the things in packages, big focus on pure Linux configurability (pure /etc files, no Ubuntu(or SUSE?) "you need working X.org to open distro-specific graphics card settings") and AUR for things there are no official packages for. Turned out it was a match :)