It really all depends on what your personal fitness goals are.
In most fitness centers today, when you walk in, you will see aerobic equipment (treadmills, stair climbers, etc,) on one side of the gym all grouped together … and all the weight training equipment (weights and resistance machines) on the opposite side. This is the perfect visual representation of the split between the two.
Aerobic exercise are those activities (walking, running, cycling, swimming, dancing, etc.) that helps to get your heart beating and produces heavy breathing. It works your cardiovascular system – the one that pumps your blood throughout your body so that it delivers oxygen to your internal organs, and cells.
Resistance exercise (also generally known as weight training) works your muscles, tendons, and bone structure in order to build strength. This is accomplished by creating small tears in your muscles, and as your body repairs them, they become thicker and larger – thus building up muscle mass and strength. It could be free weights, your own body weight, resistance machines, or even resistance bands.
Which is best for you?
The honest answer is both. You can focus on one, but you should do the other at least a couple of days per week.
Facts are, both aerobic and resistance workouts build strength and increase the cardiovascular system. It’s just that they each focus more on one.
Find the workout routine that provides you the most motivation and keeps you excited about getting in shape and losing weight, if that’s your goal. It seems that most people start out with the cardio workouts and that’s a good start for anyone.