Tender coconut water direct from the coconut will beat any synthetic drink out there any time. The place where I come from, its given to old and weak people to get energy fast. It provides easy to absorb sugar for your body.
Its pure, no chemicals and naturally protected.
The taste depends on how fresh the coconut is and when it is actually plucked. If you drink it right after plucking, it has the bubbly feel (the kind you get from light carbonated drink). But if you are getting the coconut after 2-3 days of harvest, then the taste could be horrible.
But the ones available in cans, i'm not sure.