I wish Craig would have included his sources for which research he cites here…
Should You Use Social Login’s?: “Wondering which social logins are the most popular option among users? Well, according to research, 42 percent of social logins use Facebook while the remaining alternatives are fairly equally distributed among Yahoo, Paypal, Google and others. If you can only select one form of social login…make it Facebook.”
Regardless, if you’re going to use social plugins for commenting, subscriptions, engagement, sharing etc on your site, I would hesitate to decide on just one to elevate unless you do your own careful research and heuristics on your actual site(s).
For instance, I have sites that receive the majority of their “social” traffic from Facebook and I have sites that receive virtually all of their social traffic from sites like Reddit and Twitter.
All traffic is not good traffic. Having passive visitors from Facebook that have nothing to do with performance marketing is grand, but doesn’t do much for the bandwidth costs of this site. Similarly, passive Twitter or search traffic that arrives at one of my niche book sites doesn’t do much for me (beyond pageview ego petting) compared to the Facebook or Amazon search traffic that supports and livens those sites.
So, as always, remember that your site is doing a job for people. Figure out what that job is for people and offer them the service that you would want if you were hiring your site to do a job for your mother. Limit their choices, walk them through the process, do friendly follow up and make them want to refer you and come back (as Jangro reminds us, make them yours).
Check your stats and see where the bulk of that traffic might be coming from and why and then decide if you want to elevate a social login (which you definitely should) service on your site.