I have been using Airtel broadband since 2013. And I never had any Complaints regarding services, connectivity or speed. The prices have gone high but still they are in my budget. Speed is great. 8 mbps means 8 mbps all the time. Never faced a service connectivity issue. I earlier used to use Tikona Broadband so I had to switch to a more reliable connection.
Would recommend AirTel. Last year I also got a free Wi-Fi Router. However it was a basic one. but at least it worked fine.