@ajroach42 GNU Social was written by leftist free software advocates from https://social.umeahackerspace.se/ . Also, the many quitter-sites like quitter.se, quitter.no and quitter.es, and sites like gnusocial.de or gnusocial.no definitely aren't "free speech maximalists".
Pleroma is not related to gamergate (or political in any way), it's just a lightweight OStatus server written in Elixir that implements the GS and Mastodon APIs.
There's also Friendica http://friendi.ca/ which implements multiple protocols (OStatus and Diaspora, AFAIK).
@ajroach42 I actually hope to do some reviews of the platforms soon. Really depends on what you're going for - there are short-form and long-term form systems, some of which inter-federate.