I am using airtel postpaid for about 2 years it’s is the best in class mobile service it comes with 2G, 3G and 4 G LTE networks. In this to years I never felt any signal problem even when travelling to remote areas.
The only concern is about the internet post usage data charges which are very high where as some other service providers are giving unlimited 2G as post internet data which will not cost. It will be better if there are changes in post data usage charges.