Well BSNL is available in every corner of pune.
Airtel is available in some parts of Pune.
Reliance: not sure about its coverage but its available in Pune
Sify: good but poor organisation.
Tata indicom: personal suggestion -dont go for it.
BSNL is a good option, speed is terrific but u may hav to suffer from pre installation proceedings (it took me 3 months). Customer care is shite and be ready to mug up some technical jargon.
Airtel: SDSL(same upload download limit), customer care is good, even speed is good.
Reliance: Good tariffs, service is a bit less than Airtel.
Choose among the above three...