PG, SG or SF - are the best candidates for many shoots. But this depends on player Skills and the quality of their match ups on the other side.
So if you have an poor Shooting PG vs and good defending opponent, he won't take much shots. But if the PG a good shooter, and his opponent can not defend him he will take more shots.
But it isn't all about Shooting in comparisation with defending, a good passer will often see an better oppurtunity and will pass the ball to another offense Option, a good driver will creates some easy shot for himself ...