I own the first 3 Civivi knives that came out, and my favorite by far is the Praxis. Melts in my hand, very thin behind the edge, larger knife with an awesome blade shape. My least favorite is probably the Naja, just very big and chunky with a thinnish blade grind, just seems unnecessary, my 2 cents.
Overall fit and finish on all 3 of my Civivi knives are superb though. Definitely don't feel like budget knives, and the steel is up to par for knives you'll find in the $60-$100 range with the same materials used.