I spend the extra moeny and buy my kids (22 &14) wipperman stainless steel chains. They last, they have the con-ex link - which makes chain cleaning easy - and, overall, I find (being the one who pays!) that they last longer.

My older son rides alot and races a little. The younger one races and rides alot - and a new chain at x-mas doesn't always get used right away - sometimes it August before he changes it.