Answer by Musthafa Ullal:
Go for Facebook commenting system, it will bring more users from social network and most of them will comment on his or her comment, thus phrase in conversation. To show this conversation to search engines, you should pull the comments from Facebook to your blog commenting system so that the se will index those comments too. You can do this by installing "seo facebook comments plugin".
You have the option to hide default comment system and hide the pulled comments too, which will be available for search engine crawlers. TRY It. I am in mobile so i am not able to add the plugin link. Please find in WordPress repository! Isn't it social + seo friendly?