Unquestionably, the Levator Labii Superioris Aaeque Nasi is by far the most important "showcase" muscle.
That said, calfs are important as well. Nowadays most of the topmost competitors are genetically weaker than average in this crucial muscle although they do improve on their calf size through training somewhat. Unfortunately some of them inject their calfs with a deformation oil which leaves their calfs looking just that....deformed.
