I am using mobile support service of Aircel from last 5 years and I can affirmly say that it is one of the best telecommunication service provider in Mumbai.
About range, it provides decent coverage of range( where other leading service providers are unable to provide the same.) with great internet services such as "POCKET INTERNET 24".
Also it has low calling rates if you add on Value Added Services such as of Rs 33 where you are charged half paisa per second. I can defiantly recommend Aircel as a communication service provider.