OK, this is just to help me along in getting promoted to Corporal...
My absolute favorite is the Vandron. I use that set, with tweaks, as the ships in my home games.
There are a few close seconds. That new Orion Empire looks great, as does Hugh's Swarm, and the Pandorans too. And I must admit that I have a fascination with the old NASA set I found the link for. If I get crazy enough to jump into PBW, that's probably what I would use (with a few switches from other 'low-tech' shipsets).