The most important thing here is for you to know who your audience is. The people that you are marketing to will determine what language you need to use. I think though that you can never go wrong with English, as most of the world can relate to that.
If you want to go local then try to use that language. Because Hindi is not entire India's language. And English seems to be good for some brands. In some cases using both definitely helps. Having local touch to your business can help in long run. But your work with any domain is that it should have some local indian touch in logo or domain name. That's how it may get more users.
Both is the ideal deal. But it all depends of market. For niche products in India, english would not work much, but for ecommerce and global entertainment business english is prevalent as the vehicle language.