Aircel gives excellent signal in metro cities especially Chennai, where in rural areas also one gets full coverage. Both data and voice plans are good and cheaper than other operators. In Rs 399 we get 3GB internet on aircel whereas airtel gives 2GB in Rs500.
Call rate plans are also excellent. Only problem one can get is while traveling to class b cities like Patna, coverage is not good, it catches 3g signal signal only in the main city.