In need of a new chain, please help?

I ride a lot of XC and Free ride as well, I have busted a number of KMZ chains some in less then 50miles. they are utter crap now and don't shift that well. BMX even switched away form KMZ now for shadow and wipperman. for your XC bike you will notice a big difference in the shifting with a Sram or shimano chain. I been using Shimano for a while now and have never busted one.