Hi , u have to make this topic in the consumer electronics -> dth forum ,
I cant recommend u the best plans ,but pricing of airtel is cheaper then tata sky , service wise i personally feel tata sky is better , Dish tv dont have much idea but airtel and tata sky is supposed to be better then dish tv/sun tv unless you are buying it for regional packages ,
You cannot run all 3 tvs from a single connection AFAIK , say u connect to two tv sets 1 using hdmi and another using AV out (should work mostly not sure) , u wil have to watch the same channels on both as both are controlled by single set top box , you wil need 3 seperate set top boxes , i think tata sky has special plans for multi set-top box buyers not sure just enquire with the CC