Thanks for sharing your blog in the email. You had a clear and thoughtful approach in your analysis. Your wording is clear in your motivation for choosing these sites and which aspects appeal to you. I haven't been on Quora much, but your review of the site made me interested to go back and look into it further.
I also think Amazon is great for the user reviews and they basically have information on every product there is. Even when I have no intention of buying at Amazon I still use it as a resource.
Your blog was written very well and that's a great talent to have. The aspect which could be improved upong is in the styling. I'm sure as you will become familiar with the possibilities in CSS this will evolve. (I just saw your second blog and it's already a big step forward!)