No online company is perfect in India. But in my opinion, Flipkart comes close. They have been repeatedly reliable with my orders. The products always come well packed.and so far, the orders have always come ahead of their promised delivery times.
Even my occasional interaction with the Customer Support team regarding one of my orders has been straightforward and satisfactory.
In terms of Airlines in India, IndiGo has established itself as a consistent and reliable company. In terms of online retail in India, I believe Flipkart has achieved the same.