OK. I have made an Excel Sheet that gives a comparison based on channel coverage only.
1. Dish TV offers more in content
2. TataSky offers better quality
3. STB User Interface is better in TataSky
4. Have not seen BigTV and hence cannot compare
5. Quality "is not equal to" quantity
6. All that glitters is not gold
People can extend this discussion further. They can, for instance, comment on quality, service, support, web site, etc. on each provider.
You can download the XLS, edit it (for genuine corrections and/or additions) but write your comments in the post only so that they are easily seen. I did not consider FTA and Regional channels. But you can comment on the same too. Someone can add a Sun DTH column in the XLS.
p/s. Do not download the attachment to this post. The latest one is on post # 14.