Water will hydrate you. Sports drinks will hydrate, but will also provide calories and some electrolytes. The best way to add calories to your drink is with sugars; HFCS, sucralose, maltodextrin.....
There are some companies that are making tablets you put in your water which add electrolytes - mostly salts and potassium. Brands that I know are GU, NUUN, Sportaktive, and there may be a few more. You can also buy electrolytes in pill form, kind of like a good old fashion salt pill. Hammer Nutrition makes Endurolytes, and Salt Stick makes some pills too.
Either way, there are a ton of options. Sport drinks are not bad, good way to add some quick calories when you're burning them. That said, sport drinks are bad when you are not burning calories.