I think whatever defense a team plays is dictated by the personnel they have. In reference to most high schools, a coach has to be flexible enough to possibly change his offensive and denfensive scheme periodically in order to be successful. Remember, it is not college where you are recruiting for a system. One year you may have a big slow team and a couple of years later a smaller quick team. You should run an offense and defense that gives your team the best opportunity to be successful and play to your strengths. Whether you play man or zone if pressure is constantly (should be) applied to the basketball when it is dribbled, passed or shot it will definitely increase your chance of success. I prefer man to man but any defense that allows the ball to enter the post and the opposing team to shoot a large number of high percentage shots will most likely not be successful. Teams that play an agressive man to man starting at half court and continually allow the offensive player to get to the paint off the dribble have not been taught the basic principal of staying between your man and the basket. The paint is the highest percentage area for scoring.