Agree with this. For mainly calls, BSNL. Data speeds are slow but for something like just WhatsApp or Maps, BSNL should be fine as well. Just don't expect to stream though.
If JioFi is working in your area then Jio sim will also work as calls works on data in 4G VOLTE and since you are getting data without any breaks there will be no problem, don't know whether JioFi sim can be used in other phones and can be used for voice calling,
You can try and confirm it for us.