I'll start first.
Parabola is if you like to have the bleeding edge of everything, and want to
configure your environment yourself.
Trisquel is no-nonsense for home & work. Works out of the box, if you're into
that sort of thing.
gNewSense is Trisquel, but more stable and tested. Use this if you want to
change as infrequently as possible, need a stable workstation, or run a
server.
Ututo is if you want to configure everything to the n-th degree.
Dragora is for users wanting a simple, very UNIX-ish desktop or workstation
to do development, Emacs, etc.
Musix and dyne:bolic if you are a musician that is into dormant distros.
BLAG if you want an RPM Trisquel.
