eXo Platform is an open-source social-collaboration software designed for enterprises. It is full featured, based on standards, extensible and has an amazing design.
Limited extensions or plugins available. Some custom programming may 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.