According to my experience of 3 years I will recommend Paytm.com for online shopping, almost 95% of shopping I use to do through Paytm.com because it not only gives us discount as others online shopping sites does but also Paytm.com gives us cashback which is an unique advantage provided by Paytm.com.
Those cashback varies from products to products and depending on the promo codes used.Those cashback can be used for mobile, dth, other bills payment and can be used for further shopping. So go for Paytm.com instead of other sites. But for any reason the product you are wanting is not available then only go for other sites.