Obviously, we want to acquire as many facebook likes and google plus followers as possible. Keeping SEO as a priority, if I had a choice for an extra facebook like or google plus page follower, what would you choose?
Yeah, but which kind of traffic brings in MORE MONEY to you? Facebook or G+ traffic?
If facebook users convert better on your site, that probably means they like your content more than G+ users, which means they will probably recommend your site to their friends and (eventually) lead to increased rankings (I am guessing).
In the meantime, you are also getting more people to your site who are more likely to get earn more money for you.