Whichever route you decide on going, the one overlying factor that will dictate your success will be progression! Never workout aimlessly. Make the most of your time. Stick to big compound multi jointmovements. Keep a logbook of every workout as well as the reps and weights that are used. Then the next time you do that workout/exercise again, aim to beat your previous bests either by weight with the same reps or the same weight with more reps.

There is no one special workout routine (within reason)that will produce significantly more gains then another. Just make sure you progress. Given your age and assuming that you take in enough calories, this shouldn't be difficult.

Any questions, feel free to pm me.