The worst shock is a shock with poor shock caps (cough.. Traxxas.. cough)

Or shocks that utilize wet noodles molded together into a shock shaft (looking at you Integy)

But so long as you have those covered, the worst shock for bashing and racing alike.. is a poorly built/setup shock. Build them right and set them up to compliment the chassis and what you are going to be doing with it, and any shock of half decent quality will do just fine.