If we go for cryptocurrency to buy/sell india then with secure and instant payment some websites are there from which of them one is Unocoin.
Unocoin is gives good services in compare to other but for verification of your account they took little longer process but that does not matter much in my opinion because it is the process for securing your transaction .
For Android/smartphones they have their app of Unocoin which should give better support.
But in my opinion you should choose their desktop which is work more accurately in compare to App on android.
I recommended because some people complaint that app is not working properly and similar things but may be after complaint they improve their performance of app.
On Unocoin you can basically buy and sell Bitcoin .There are many cryptocurrency but Unocoin only support Bitcoin exchange/buy/sell.In compare to other they take low fees of their services means for creating wallet they will not take fees but if you are going to buy or sell BTC then they will add little amount of fees on that purchase/sell for instant money transfer service.
So in my opinion overall Unocoin is good.