Biz/Eco? Dates?
If you can specify a date, its very easy to check.
If economy, the cheapest is AA miles. But from an Indian CC perspective, the other options would be to check Turkish or Lifemiles for a direct flight (United will be a little expensive using miles). For other options (1 stop) Avios would be a good point to check via Aer Lingus and Iberia.