If your looking at doing a s15 face you should definitely use only good quality parts, seems the brands you listed there qualify. Too bad everyone is jumping on the s15 face trend recently, so you should try something different to stand apart from all of the VIS and Version select users.
I went with the GP sports G4 front since its extremely simple and clean with a fat lip on it. Also at the time there was only one documented car with it and that was in Florida, and I am in California, so no chance of seeing my kit one someone elses car. (P.S. don't go with this kit, be a man do the right thing)
As far as my personal preference goes, I like s15 bumpers that don't have the vent/grill in-between the headlights since it gives the car a sleek look. The opening messes up the look and makes it look similar to a late model s14, however im sure the grill opening allows better cooling, whatever moot argument.
If I was to replace my bumper in the case something happened *knock on wood* I would pick from these three.
1. Top Secret - Similar to GP G4, but with a wider center mouth and side vents
2. Yashio Factory - Like Top Secret but no side vents
3. Do-Luck Aero Wivern - Aggressive looking, never seen it on any car
All of those are probably $$$ but if your doing a conversion I assume you have $$$ to blow on needless cosmetics anyways...