Well, between DishTV and Tata Sky - there is not much of a difference. In fact, price wise all the DTH service providers are at par in the current scenario.
As far as channel count is concerned, DishTV had the upper hand till now. However, with the latest additions Tata Sky has been the service provider with the high number of channels. Tata Sky has recently added a host of new HD channels. Besides, as far as the addition of newly launched channels are concerned, TataSky takes the lead in comparison with DishTV.
In terms of pricing, Tata Sky has always gained the distinction of being expensive. However, with the current trend, the cost of package price across all the service providers remains almost same. However, price wise DishTV has a slight edge over Tata Sky.
Customer care service with the Tata Sky is of professional standard. They excel with prompt resolutions for almost all of the problems you may face while using their services. DishTV has a slightly tarnished image when it comes to the after sales service. Not that it is similar across all the cities, they seem to have quite an excellent service across certain cities. The issue is with their local franchisees. In essence, if you want better after sales service, it would be a good idea to opt for Tata Sky.
Quality of service
Picture quality is definitely of top class in Tata Sky. Not that DishTV lacks much, but since they are still sticking with MPEG 2 - they have been facing space crunch and as such need to have the higher rate of compression.
Tata Sky beats DishTV when it comes to the UI. The interface is clean and stylish in Tata Sky. The menu in Tata Sky is clutter free while navigating through the menu on DishTV is a little difficult.
As far as the service level is concerned, almost all the DTH service providers are almost similar with a very little difference here and there. I would advise you to check out the packages and decide on a service which offers better pricing for the channels of your choice.
Live....and Let Live!