[FraaJad]

In the decreasing order of priority

  * twitter
  * github
  * google
  * ... many many galaxies later.
  * facebook.

[Ecio78]

It depends on the target; i'm thinking about my friends (most non-techie), from most spread account to least spread:

1)facebook

..some planets later..

2)google

..some solar systems later..

3)twitter

..many galaxies later..

4)github