As the king, it serves nothing if my knights grovel and kiss my royal arse. I want every man in my army and the woman who serves me all focusing on the same thing: the enemy. The enemy is that way (points toward the opposite side of the board). Thus I play with my knights pointing straight across the field.
Optimal Knight Orientation


I orientate them towards me. But why do I do it? Because of 2 reasons: To show my oponent how creative I am and see the reaction of his face.
I point them facing directly forward.
Most players seem to do this. Though, as pointed out earlier, it might not be the optimal approach, as it makes the pieces' appearance on the board less distinct, and grasping them is a bit less comfortable as well.