Go to ability in most cases
My suspicion is the Gargoyle is OP at the moment. It may only be Jade Dynasty Gold in situations where the death knight needs a lot of burst on demand, but it definitely seems more popular than we suspected it would be. Heart Strike should be your go to ability in most cases. When you are at risk for breaking CC, you can use Blood Strike instead. But the intent is that Heart Strike will do more damage. It competes with Frost Strike and Scourge Strike in the other trees.