Motion Of Non Suit Or Make A Defence Argument?

The crown needs to prove a key fact in order to convict me, and I know she has no evidence in this regard. Would the usual strategy be to raise a motion of non suit immediately following the crown's presentation, or would I simply make an argument in my defence that the crown has not brought a prima facie case?

In that situation a person could make a motion for non-suit or simply call no evidence and then make submissions on it, or both (assuming the motion was denied).