Hi I have been using Airtel connection in Delhi for the last 4-5 years and alternatively been using idea connection in my other handset as well. After years of hands of experience I must say that Airtel stands the best in India.
Speed of ISP connection- Amazing
Connection Reliability- The best, compared to any other connection
Service and Support- Good, can easily connect to customer care executives unlike other connection networks where it is very difficult to connect to customer care executive.