@nishantt6969 This is a difficult choice. Really. They are both top notch service providers. Comon if either of them wasn't good enough Id have disconnected one or both a long time back.
Anyway, IF I had to choose just ONE it would be Airtel. Why? Public IPv4 and their willingness to go the extra mile. I;d say Airtel is 99/100 and Tata Play is 98/100. Again let me stress this is based on my experience, in my city. So my rating is very subjective. Take it for what it's worth. People have had good and bad experiences with both as per posts on social media. Your experience may differ.
Jio was supposed to set up their service in my colony but an infra problem has delayed it. I am not worried though with Airtel and TPBB around.
No, you can't configure it yourself. That is done from their backend server. It is a /64 PD and you need to set up your personal router, if using bridge mode, to properly work with v6. If you use their OEM Nokia/Dasan etc then it is delegated automatically and nothing needs to be done.