Kind of an old thread, but whatever.
As far as build quality, of what is available Grillcraft is better. My problem with Grillcraft though is the style. I could give a damn about the cost, I just can't stand how the Grillcraft sits flush with the bumper. yuck.
I always liked the grill to be recessed in the opening, like on the Modern Image/TSW/WetWorks Spyder:
That is how I made my grill sit. I had three different grills, and used material from G2 and APC (I used black mesh G2, black mesh from APC after I damaged the front end, and then silver mesh from APC just to change things up). The mesh material from either brand is sold in universal sheets, and has a good diamond-shaped design. The grill itself is thinner than the Grillcraft so you can cut it to fit, but its not too flimsy that it falls apart. The G2 was about $25 for a sheet big enough to fit the front opening, and the APC was $40.
I removed the front bumper and placed the grill on the backside of it--there are little tabs across the top of the lower opening, which held it enough in place to reinstall the front bumper. The mesh would fit very snug against all the plastic crap that you can usually see in there, so the fit was tight as can be.
Because the grill is black, it doesnt show up all that well in pictures. So, bear with me

These pictures are ooooooooold:
And this is the only picture that the silver grill showed up at all. Much newer pic:
Anyway, unfortunately we don't have much choices with grills--besides Grillcraft and StreetScene, all of the "companies" making grills for our cars are essentially guys making them in their garage. None of the higher-end grill companies make them for 3Gs, nor do any of the European companies who make such damn nice stuff for the euro cars. It's not like Grillcraft is all that great of quality/fit/finish either, its just the better of whats available. So if you don't like the style of Grillcraft, you will likely have to make your own.