As someone who has been on a buying spree for over a year now (shopaholic ) let me rate the popular websites on a scale of 1-5 (1 being the lowest)
Parameters considered:
A. customer service (calls, E-Mails, chat)
B. shipping (packing quality, time taken, shipping costs)
C. genuineness of products (old stock, condition)
D. deals (discounts, offers)
E. website quality (ease of use, mobile version)
The best
Flipkart - A5, B5, C5, D4, E5
Amazon - A5, B5, C5, D5, E5
Lenskart - A5, B5, C4, D4, E5
Snapdeal - A4, B5, C4, D5, E4
Mid tier
ebay (powersellers) - A3, B4, C4, D3, E5
Zovi - A5, B5, C4, D5, E3 (when you add many items in cart the discount coupon box vanishes from bottom of screen)
Jabong - A4, B4, C4, D5, E3
Myntra - A4, B4, C4, D4, E3
Pepperfry - A3, B3, C4, D4, E4
Homeshop18 - A3, B3, C3, D4, E3
Back benches
Shopclues (reputed sellers) - A3, B4, C3, D4, E2
Tradus - A2, B1, C2, D3, E4
Rediff - A1, B1, C2, D3, E2
Infibeam - A1, B3, C2, D2, E2