These are a good shout too:
http://www.tartybikes.co.uk/chains/kmc_z510_18_inch/c7p11566.html
I run them as they are £6 cheaper than the Z610 HX, and are nearly as good.
Change them every 3-4 months, and fit them correctly (by either using the split link provided, or taking your time and lining everything up correctly when joining it back together) and you won't have an issue with snapping chains anymore