Depends on your objectives and situation. 1) gamedev => MonoGame 2) business (SQL DBs) => NHibernate 3) web => SignalR I personally never learned by participa

Depends on your objectives and situation. 1) gamedev => MonoGame 2) business (SQL DBs) => NHibernate 3) web => SignalR I personally never learned by participating in OSS but times change.