I've had good luck with SRAM chains but again, obviously not enough data points to matter.

Do you do a lot of shifting under load on your MTB? This can cause premature failure. Tiny MTB granny rings put more tension on a chain than just about any other application. Obviously they should still not break, but if you're hammering on them and "power-shifting" a lot I wouldn't say it's unreasonable. Are your chainrings/cassette badly worn? Again, this won't help.

+1 for using a Shimano chain and SRAM link if you're unhappy with SRAM chains.