Different rounds have different advantages for different situations. I guess for general use, the S&W .40 is a very good choice. But I think my favorite gun is my .44 mag Desert Eagle, extremely well engineered pistol. Israelis know their guns.
My two cents...I love and own 2 Sig Sauers...9MM and the .357 Sig are my calibers of choice. As someone already said, different sizes for different situations.