Recent offer from Airtel (Airtel Call Home) ($10/month) attracted many people and now airtel has increase the offer price to $ 14.99/month and its charges of 1 cent/minute apply only when you call a mobile number in India. To landline its 2 cent/minute.
I don't feel this offer is so attractive for everyone as you have a validity of 30 days for your recharge so it will depend on your usage pattern. Several years back Airtel had lots of billing issues and many people have quit using it after that.
Rebtel (Rebtel Home) charges 2.9 cents/minute and its also a reliable provider. I have seen their billing is proper and I like the direct numbers they provide you to make calls unlike other providers where you need to call the toll free and then dial your number. Rebtel's website looks better then its competetors
Reliance indiacall (Reliance India Call Home) has also come up with recent offer of 1cent/minute, but with a recharging validity of 7 days. Which makes it dependant on usage pattern.
Union Tele card (Union Telecard Home) is another cheaper option with decent billing and reliability. Their recent charges were 2.8 cents/minute, which is competetive to all other providers.