I love all the Sinnoh starters for different reasons, but as for competitive I went with Infernape. It can hit very hard and fast, and fire/fighting, while boring, is a good typing for an attacker, especially a mixed one. Unfortunately Torterra has that 4x ice weakness, and while it's bulky and can set up, 4x common attack weakness + no speed makes it not the best. Empoleon never seemed like it had enough in defenses or attack for me.. or speed? Something always seemed to be lacking.