I recently switched from BPL to Airtel and glad that I took this decision. I get much better clarity, better reception in closed rooms and also better battery life.. which itself is a indication of good signals.
Although I havent tried it on outskirts (as now a days I rarely go out of Pune) but in city it is way ahead of BPL. Also they provide 32k sim card which can store 1.5 times more number than my old BPL sim card. It also provide a extra menu item where I donnt need to remember the sms codewords.
Uptill now I didnt have the trouble of network congestion also.