“is the best?” – that is going to be quite a subjective answer from whoever may answer it.
The best one?! One that does not use facebook at all (IMHO) – privacy. dependency. more important than making it easy for that one person who might actually use it.
If you want to find what you think may be best, install a few from the wp-repo and see how they work, and how they work.. you may find the one that looks best with your theme is what you think the best is.
I will never use a plugin that phones home to Ggl and Fbk for my site to function – it’s bad enough when gravatar slows down page loads – and privacy is not just a personal issue – but in some cases a country laws issue (look at http://www.heise.de/ct/artikel/2-Klicks-fuer-mehr-Datenschutz-1333879.html (might have to paste the url into a service that will translate the German to your language)
from the author of “2 Click Social Media Buttons ” – from what I gather some of the common WP things people are deploying are in complete violation of various Euro laws.
(looking at your Google Fonts auto-embedded in WP, and Emoji third party calls, and many theme’s auto use of CDNs for things)
and plugins like “Social Media Feather”
are the kind of tradeoffs I might consider when a project requires some third party stuff.
OF course I am no expert on any of this, just some random BP user. Your opinions of whats best may differ.