Originally Posted by OBoile

All types of exercise have benefits and drawbacks. What is "best" ultimately comes down to the individual. Running is great for a time pressed person, but poor for someone who can't stay healthy when doing it. Is there a pool nearby and what are the hours it's available? What you enjoy also matters.

But, for overall fitness, you should be supplementing your cardio with some strength training... especially if what you do isn't load bearing. Muscle loss due to aging is a big factor in future quality of life.