What is Black's Best Move to Checkmate

Hey All Others,
What is Black's best move to checkmate White's King on the last move? Is there some chess principle or rule of thumb to play 1 move over all other final moves to checkmate White? Or even, are there some chess principles/rules of thumb to properly play the last few or so moves of Black's in order to properly checkmate White's King?

If you do comment, fine. I am not asking about checkmating White's King in as few moves as possible, but really asking, "are there positional reasons or other proper reasons to play 1 or more moves over another or other moves?" Or is it simply player's choice in this case? Or is it only a matter of trying to checkmate white as efficiently as possible?

Ken

Here is the Blitz Game:

The variation KnightStalker47 wanted to show.