As a project, Pleroma seems to be doing all of the things Diaspora should have done years ago.
* Good collaboration between many different individual contributors
* Coherent goals for what direction the project should go in
* Regular updates and improvements that usually don't break everything
* Heavily invests in architectural improvements and early optimizations
* Regularly evaluates what sets of APIs and features to support
* Tests federation between different platforms to debug issues
* Constantly thinks about how fediverse communication apps can be better