Hi, this isn't going to be the most in-depth and fancy post, but I just quickly would like to point something out...
Every once and awhile, I'll take a keyword that I'm using for the site, modify it a little, and do a Google search intending to find some great ranking sites to leave a comment on. I'd say that 35-40% of the time, the only option given to leave any comment at the end of a post is through a Facebook app.
This may work out well for some, but is very presumptuous, assuming that everyone has a Facebook account. Personally, I don't have a Facebook account, therefore I leave the page without being able to leave a comment. With many people being turned off by Facebook and finding out what else is out there, I can't be the only person who this happens to.
So I would suggest that you stay mindful of the options available to your visitors as it relates to engagement, because as we learn here at W.A., comments are very important. To date (12-8-2016) My site has received 807 comments to the site. 159 of them are from the comments section here at W.A., the rest have come organically via this generic appearing comments box in the picture below.
In my opinion, this is the best way to go for your site, if you're looking for the most possible organic comments to your posts and pages. No frills, and rather plain, granted... But how many people have ever failed to leave a comment because the comment section wasn't pretty?
If your content is good enough, then that'll do the talking for you. And having convinced someone engage with you via a comment, they're too busy wanting to throw their thoughts down into the comment box, to formulate thoughts on the appearance of the box itself.
So, don't miss out on any organic comments coming your way by placing all of your eggs in one basket. Keep the options open and available for your readers.