As you know that these are all social community networks and some of them have much popularity and some of them are just began. But i consider zenzu would be the best one in terms of earning money. Orkut and youtube have not that much efficiency for that. tell me now... You know zenzu will give massive income just for logiin and log-out 30 times in a calender month. so u decide which one is the best i need your feedback.now... for more info u can click the link below: u need it.
IMO,i think youtube can earn more money if you have adsense account and know how to promote your videos. And there is less work involve if compare to zenzuu such as need to login and logout every 30 minutes