Elgg is an award-winning social networking engine, delivering the building blocks that enable businesses, schools, universities and associations to create their own fully-featured social networks and applications.
Many available extensions or plugins available. Custom programming may not be necessary.
Management of content and data is relatively straight forward, but there may be a bit of a learning curve. Some programming experience may be required.
Has a larger active community. Support is always available for free or as a paid service. Excellent documentation available.