GC2's ship builder is miles ahead of SD.
It really depends on what you want out of the ship designer, though, doesn't it? GC2's ship designer lets you make ships that looked more or less like anything you wanted them to, as long as you had the patience to place all the little pieces and had the parts you needed. It doesn't make the locations of the non-decorative parts important - as examples, the orientation and placement of a cannon had no impact on its firing arc, and where you place armor relative to other ship systems has no impact on what gets protected by the armor.
On the other hand, from what I've seen of StarDrive's ship designer, you have a fixed set of hull patterns and you can put certain types of modules into certain types of slots. It allows for protecting systems against incoming fire by interposing less important systems or armor between the likely direction of fire and the aforementioned important systems, but limits you in terms of how much of what kinds of things you can put on the ship.
Whether or not one model is superior to the other really depends on how detailed the combat model is going to be - if it's going to simulate firing arcs, armor location relative to ship systems, etc, then I'd say that what I've seen of StarDrive's ship designer is more appropriate. If it's going to be the same kind of combat as GC2 had, then there's really no need for that. And, of course, on what you as the player want out of the ship designer - if you want the ability to make ships that look like almost anything you want them to, then GC2's designer is probably one of the best out there, if it's not the best. If you want to have a relatively detailed combat simulation or have the locations of the components you placed be important, then something like StarDrive's ship designer is better (at least from what little I've seen of it).
