Which comment system you prefer using? And why you prefer using it instead of the other one?
Blog commenting for link building pusposes, back linking and dofollow.
For Blogger the default comment system is better. Many people hate Commentluv and I do not see why I should allow people to leave a link on my site just of Facebook like !!
None. As no-one want to get spam links which has no relevance, instead social sharing buttons are better. people usually made irrelevant comments with their links so it kills time to filter those; sometime with this genuine comments would also went in vain.
So better to hide comment option.