well, you just can't comment on this one both of the sites are authorative and interms of traffic both of them a almost equal. For some people facebook is their traffic gainer and for some people facebook is traffic gainer. And if I talk about myself twitter is our traffic gainer.
The spam/content threshold on facebook and twitter is very low
links to your site, without contextual reason, have a rapid negative effect
& will trip search bot algorithms
you won't know until SER disappear
+1WebOutGateway's "be patient"