What is the best teen work out you know?

Best excercise. It depends. Work outs are healthier if you love what you are doing. For some long distance running builds endurance better than most sports or hours of fast dancing. Find a cardio exercise that you love to do and this will be the best for you.
Jump rope. Teens are always moving so they can loss weight easily. Walking a lot, biking, playing especially with jumping rope and eating less calorie food.