I usually feel Jio is best for this scenario. Once you have a plan on your sim (I usually get a yearly plan), and you enable IR ONCE WHILE YOU'RE STILL in India, you're good to go. You get all incoming messages for free & you can basically add some balance to your account, and calls from and to India will be charged at 2 rs per minute. Pretty good deal if you ask me. I have a dual sim iPhone, and I always have the Jio running on it, so even if someone from India calls me on that number, i end up paying just 2 rs per min.
First time enabling IR must be done from within India. They say it wont activate outside India at all (I was able to do this by jumping thru hoops but is not guaranteed).
Also, the wifi calling will not work like you'd expect. Jio will connect to WIFI Calling, but will not allow you to place any calls. You'll get an automated message saying "Wifi calling only available in India"... so that is that.