While I have no issues with the Sobe Lifewater (I actually think it tastes too sweet and don't care for it) or the VitaminWater Zero (which I LOVE the lemonade and orange ones).... if you are simply looking for an alternative to juice for your child... why not just give them plain water?
That is what we did. I NEVER gave either of my kids juice. of any kind. It is just sugar, really. There is not enough Vitamin C in any kid's juice to make it any sort of health drink for them. They don't NEED juice in their diet. I let my kids choose between milk and water when they were thirsty, and they never had any complaints. The still LOVE water. My almost 9 yr old daughter doesn't even LIKE any kind of soda... if it is carbonated forget it. She won't drink it. :) When I get drive-thru kid's meals, she always ASKS for either milk or WATER. When the kids have b.day parties or school parties and pass out the juiceboxes... my daughter whips out her water bottle. She doesn't like the other. Every blue moon, she will want a grape kool-aid pouch... or a blue powerade. That's it.
Try it out. You might be surprised at how quickly they get used to drinking plain water. It's really good! Make sure it is nice and cold... it always tastes better that way to me. :)