The three are radically different models, yet all work very well for tactical purposes. I can speak of the Native and Starmate from personal experience, but unfortunately do not possess a Wegner. I will base my comments on the Wegner from the material I've read.
The Starmate is the most elegant model, and really was designed for this purpose. After all, Bob Terzuola popularized the folding tactical, and this is a rock-solid liner-lock model. However, the handle does not feature an effective indentation for thumb purchase, so some people modify the handle to add this feature. Personally, I don't find the handle uncomfortable, and consider it's straight shape ideal for different handling positions. The blade is 3.75" which is legal in some jurisdictions (not in mine).
The Wegner was chiefly designed for hunting and dressing game. Still, it has been reported that it handles well as a defensive knife. It's grip is second to none in that it allows fine purchase of the index finger, and it really molds to your hand. Also, the blade shape has an excellent belly for slashing, and the hollow-ground helps to reinforce tip strength (also in the Starmate). This is the most tuggedly and solily constructed of the three, due to its heft and width. This is also a drawback in that it is not so easily concealable. Also sports a solid, thick linerlock.
As for the Native, it is my favorite overall Spydie knife (do a search under username Flood and subject Native) and you'll see my many positive comments). It is the perfect balance of a utility and defensive knife IMHO. Solidly constructed, blade-length is an LEO-friendly 3 1/8", spearpoint blade shape facilitated penetration and slashing capability also looks pretty good. The finger choil and handle indentation allow for good finger purchase. Its handle length, however, is pretty short, which limits reach. I have medium/short hands so it doesn't matter much.
There's much more to say, but I think I've covered the basics.
I personally prefer the Native for utility and defensive purposes, the Starmate strictly for defensive backup (although I'm sure it would make an excellent utility folder), and the Wegner for survival/outdoors use.
If I HAD to make one choice and it is chiefly for defensive purposes, then I would choose the Starmate.
Good luck with your decision. Please let us know!
-Flood