As mentioned, Shimano make directional and non-directional chains whereas KMC and Sram don't. I've seen so many Shimano chains put on incorrectly, especially no demo bikes at trade shows, because people want the cut outs facing out. Shimano also make Road and MTB specific chains whereas KMC and Sram don't (actually Sram has moved to differentiation for 11 speed, but the Red22 and XX1 chain characteristics seem the same - besides different weight reduction).

At KMC, we've done extensive testing and feel no need for a category specific or directional chain - one chain for all In fact, our newer X10 and X11 series outer plates are asymmetric for shifting reasons but the chains are still non-directional.