I've never had a problem with KMC but then I've also had no problem with Shimano or SRAM. I am, however, a pedant for cleaning and lubing.
I've been told that Shimano have greatly increased the quality of their chains in the last few years but I have to admit that I don't get through enough chains to verify that.
One thing to note is that SRAM chains are now made by KMC, so, if SRAM are happy with KMC there's probably no reason for you not to be!!