I’ve never tried NixOS, but it looks really promising.
I usually use Fedora or OpenSUSE, which have good software availability (unfortunately not as good as the AUR). Fedora provides selinux by default, and has profiles for basically everything. SUSE uses AppArmor, but Arch doesn’t provide convenient configuration for either, and only supports x86_64 (which is why I switched away from it).
Use double n, that’s the archaic way of spelling that (tilde derives from n on top of another n)