Tata Sky is definitely better than Dish TV(which is a very good name because its nothing more than a DISH attached to your TV).
Its reception is much better and customer care is more helpful and quick. Moreover, the channel packages are good as compared to those of Dish TV which are highly Zee-centric.
Online account management and recharge is also very quick and safe on Tata Sky as compared to Dish TV.Customer Care is also good.All in All, Tata Sky is much better.