Sodas are sweetened with either sugars such as HFCS or with artificial sweeteners, making them poisons. They are also highly, highly addictive. When rats are given the choice between cocaine and sugar, they go for the sugar.
Teas, when drunk in moderation, are actually good for you. However, too much tea can cause a caffeine addition, and then if you try to stop, you will suffer from caffeine withdrawal headaches.