Most orthodontists will say anything except water is a no-no - coffee and tea will stain your aligners, and they almost always permeate the aligners into your teeth, causing decay until the next brushing. Juice is even more harmful with the sugar and fibre. Also, hot beverages can deform the aligners. I know cases of people who tried having drinks with straws, and realized it wasn't a viable solution. The drink still ends up permeating the aligners.