Hi Salil,
quality of broadband services depend upon region to region.
But in general,
1) MTNL(good plans at affordable price)
2) Airtel if available (excellent support but fup sucks)
3) Reliance "wireline" (known to give best ping out the three)
based on price,
MTNL is cheapest, followed by reliance and airtel.
Also tell us your broadband requirements so that a plan can be suggested