I have been doing online shopping since 2014 and Amazon turned out to be the Best among all. There are certain parameters to judge such as product quality, delivery system, refund/return, customer support system, best price availability and easy user interface.
I can tell exactly on all the above parameters that Amazon stands out. I have bought Moto g4 plus from Amazon exclusive sale and it was delivered to me within 2 days(Ordered at 3 am on 18/05/2016 and delivered on 19/05/2016 by 4:50 pm).
I have returned an order of Logitech audio adapter on 20 and got the refund amount of 103 in my bank account on 21st morning. On returns, they have no question ask policy. No other e-commerce site provides you with such a reliable service.