I am working with a startup which is about to do it's launch in maybe 2-3 weeks. In order to see the primary features of the site, the user has to register or sign in if they have already registered. We quickly decided we wanted to incorporate social plugins as alternatives to a conventional sign up, just like stackexchange does.

But seeing that we are strapped for time and fairly amateur developers, I'm trying to justify just choosing one or two social sign-ins to start with for the launch and then maybe add more later.

Based on my experience as a user, I'm guessing that twitter and google (in no particular order of importance) would probably be the most important social sign-ins in order to retain as many users as possible, but have absolutely no statistics to back that up other than my own anecdotal experience.

This question hasn't been visibly asked on the internet, so I figured I'd hop on stackexchange and give it a punt.

Thanks.