I am using Airtel for the last 4 years, and I must say that their coverage area is the best amongst all. I get good range even in the most weirdest places where you don’t expect coverage to be. Their pricing is something that that is really bothersome.
I have started using Airtel for only incoming calls as their tariff is high. Their top ups, data packs, both 2g and 3g and even the sms packs are over priced I feel.