Basically its the money thats matter. Products on all the three major online shopping are legitimate . There may be some errors by the pakaging companies that doesnt indulge blame on these sites.
Comparitively amazon is a better site than flipkart , but if you get the product for the same rate on both these site then plz prefer flipkart because of its indian origin. Amazon paking is way better than flipkart but products from both these sites reach u safely.