SBI has the best transfer rates but they are slowww.. They take about 3 business days more than the rest, so its upto you whether you can wait that long.
http://www.onlinesbi.com/gls
Remit2India is the best combination for fast and good transfer rates..I will be happy to refer you if you are interested. PM me. Also Remit has a rewards program called IndiRewards which gets you some goodies for transfers.