AIRTEL is the best network in India, it's my opinion because I used it since one and a half year. No network problem in all type of area like in city, villages, travelling in bus, train and also even lift and under basement of a multi. I have no issue about network on airtel.
I live in Indore, the network tower is situated in every 5 km area. I think I have not faced a network issue on airtel. I used Airtel prepaid service. The data price now a days it's rs 399 in 70 days in which unlimited calling and 1.5 GB daily. It's speed is also great as compared to others operator. The customer care service is also very helpful in 24 hours for their customers.