So far, I'm liking the UMC. I find the Federal is louder and dirty. The WWB is OK but, there's this gold finish that covered my fingers after loading only two magazines.
Interesting. Out of those, I always found UMC to be the dirtiest around. With that said, I'm not picky. If UMC was the cheapest, it's what I'll shoot. Overall I've had no issues with any of them.