I heard that both juices were supposed to be good, but that orange juice was actually the better of the two. But lemonaid was what the dr. recommended.
After a year on the kidney stone anti-diet, I had more kidney stones. Told the dr. I had not had any tea, chocolate, collard greens, salad, almonds, beets, etc, etc, drank a gallon of water a day along with the lemonaid. What else could I do, doc.? He said, "We really don't know what causes kidney stones to form." I left there and got some chocolate and some iced tea.
That's my take!
I don't have any evidence other than word of mouth - I've had more than one person tell me to drink lemonade. Something about the acidity I think.