At position Q16,D4,Q3,D17,C15, @frankiethefrank started the conversation:
Better than D15 because of hoshi at D4?
( FYI @aesalon )
No, C15 is only the most popular. Other good options include D15, approaching or invading the lower left corner, and enclosing the lower right corner. See http://ps.waltheri.net/202670