synapse

• ‘reference’ implementation in python
• can be slow at times
• has a very long configuration file
• requires to have a valid TLS certificate in the config, otherwise all seems to work, but federation does not.

dendrite

• does not always provide meaningful error messages, e.g. when files are inaccessible due to permission issues.
• does not yet have a lot of documentation
• seems to maintain its cache status in the database. Clearing the cache in the file system is not enough.

conduit

• works really good.
• adds a lightning to user names