The only 5.56/.223 brass that is significantly different than the "gold standard" (which is brass manufactured at Lake City) is Federal. Federal brass is total crap, at least in .223 and .308. It has thicker case walls, but a thinner case head, reduced internal volume, and soft brass. Most reloaders treat it like Berdan-primed brass and scrap it. Those who don't just don't have enough experience yet...
-Troy