Which SIM card is the best one for roaming, call and Net connection?

When it comes to universal connectivity all through India, nothing beats BSNL. Being a public sector undertaking, it enjoys wider network and cell sites (towers) in every nook and corner of the nation.
As for roaming, it offers you totally free national roaming. Of course, there will be differential billing for the outgoing calls depending on the visited circle. If you opt for per second billing, you will get the same for in roaming as well. Calls within visited circle will be treated as local.calls and those outside will be STD calls. It was what was practiced when I was a BSNL user from 2004 to 2011 or so. I am not sure of the tariff as of now.
More over, BSNL has no differentiation between 2G and 3G dara packs. You will be able to browse at 3G connectivity whenever and wherever you get 3G coverage on the same pack. Their data plans are more cheaper and economical than others in the market.
Only drawback with BSNL is the laid back attitude of the firm that ruins every positive traits they have. Being a government enterprise, they are constantly plagued by inconsistent connectivity. I don't have an idea of what is the status right now, but that was the sole reason I had to leave them.
As for other operators, they are not consistent performers in all circles. Though AirTel leads the pack with innovative plans and schemes, yet they have different plans across different circles.

I can't tell you about the karnataka state. However I have used the service of Vodafone in Maharashtra, Gujrat and Delhi. And I found the reception of the telecom services in one of these places without any issues.

I also found that the 3G reception across entire country is not consistent. So any company that tells you that they have 4G data with high speed is a lie. That is because the telecoms have not properly upgraded their network to 4G as of yet. So don't fall for 4G ads claiming the network is upgraded and you can get best data transfer rates.

I'd say stick with the network which has better coverage in your state. Depending on where you work and the places you travel, choose the SIM that suits your needs.

BSNL is the best for free roaming, calling and net pack.
Recently BSNL has announced free national roaming.
BSNL is providing 3g datapacks on 2g rate.
Connectivity of BSNL is good in villages also.

Telecom companies takes advantage of people's demand of good services. But after great demand of these companies by people. They are rising their packs rates whereas charging high rates over calls and roaming as well.

If you are asking for best telecom service then I would suggest you to blindly go for BSNL. Being under government it gives very good rates over calls. Recently, they announced free roaming all over India. While every omelet companies were raising rates of internet, they did same for 2G and converted them to 3G. If you are opting for BSNL then you get 3G internet services at the price of 2G. Apart from all these BSNL have massively evolved and gets very good coverage in remote areas as well.

So go for BSNL and support Indian government.

Regards,
Joy Joon

I think the best SIM for roaming is either BSNL or Reliance as per my experience recently, the next one come Airtel that also works fine in remote area except few places. Other all are working fine in only particular places and not upon travelling or remote area etc.