Dartagnan64
G.O.A.T.
There is kind of two ways to answer the OP question.
There is the hardest shot based on the incoming ball and the hardest shot based on player execution.
Hard balls to face: 1) Any winner/ace (if you can't touch it you can't return it) 2) volley at your dominant shoulder 3) high ball to your BH, 4) low slice with side spin, 5) kick serves into your body
Hard shots to execute: 1) Running back between the legs winners 2) hard and accurate serves 3) Backhand smashes 4) midcourt swinging volleys off lobs 5) drop shots from behind the baseline
There is the hardest shot based on the incoming ball and the hardest shot based on player execution.
Hard balls to face: 1) Any winner/ace (if you can't touch it you can't return it) 2) volley at your dominant shoulder 3) high ball to your BH, 4) low slice with side spin, 5) kick serves into your body
Hard shots to execute: 1) Running back between the legs winners 2) hard and accurate serves 3) Backhand smashes 4) midcourt swinging volleys off lobs 5) drop shots from behind the baseline