Whatever you will do. The best sport or exercise is whatever you will do regularly, really.No one sport is "better" than another, although different sports will have different effects. For overall health, including a sport that has cardiovascular benefits is very helpful (running, walking, bicycling, etc).Yoga and tai chi give flexibility and balance.Weight-lifting is good. Caution with overdoing, but get out and get fiti.
Best exercises. For optimal fitness you want to engage in at least 150 minutes of activity each week. These should be divided into 3 areas: 1) aerobic: jogging, hiking, treadmill, elliptical, etc. 2) strength: low-medium load weights for strength, upper & lower limbs; and 3) stretching or yoga for flexibility.