Both hot and iced are good for your health. The only difference is that the two categories are suitable for being used on different occasions. For instance, hot beverages are often preferred during the cool and cold times of the day. Iced tea on the other hand, is best when consumed during the hot times of the day, especially during summer.
You would enjoy a refreshing glass of iced tea during summer more than you would enjoy the same glass during winter. Runners are encouraged to prepare their drink hot or iced depending on the occasion during which it is to be consumed.