Th3ory is the developer of unleashed, which was renamed to r3blurr3d, so same thing. You can see the thread about it and read all us raving about how great it is:
http://forums.androidcentral.com/bi...h3d-v1-0-blurry-moto-kernel-09-22-2011-a.html
Haven't used liberty so I don't know.. I think they kind of appeal to different tastes though, as liberty from my understanding is a more vanilla android ROM while r3blurr3d keeps in the motoblur aspects but has tremendous tweaks to improve them.
The beauty of this world is you don't have to get married to one or the other... flash one try it out a few days or something, whatever you want, then wipe and flash the other. Go back and forth as much as you want and figure out what suits your tastes best.