FireCMS

vs

MODX

Primo is an all-in-one IDE, CMS, component library, and static site generator. With Primo you can build sites faster, add and manage content more easily, create an actual, usable component library, and publish a fast, secure, cheaply-hosted static site.

With Automad you can manage content easier than ever. Automad is a file-based content management and template engine that allow you to create fast website without the need of a database. Instead all content is stored in human readable text files which makes it easy to put a whole site under version control with Git. The elegant admin panel provided by Automad includes a block editor and the in-page editing capability. You can also extend the core of Automad by creating your own packages or making use of the once already created by the community.

Backdrop is a full-featured content management system written in PHP. The Backdrop CMS allows non-technical users to manage a wide variety of content. It can be used to create all kinds of websites including blogs, image galleries, social networks, intranets, and more.

October is a free, open-source and self-hosted content management system written in PHP on top of the framework Laravel. The CMS features a universal extendable dashboard, inspector, reusable CMS components and a plugin system that can be used to extend functinality of your website. The plugin store contains thousands of community-made plugins that can either be purchased or installed for free. As a data store, October CMS supports MySQL, PostgreSQL and SQLite.

WordPress powers roughly 30% of all web pages online. It's a free and open source CMS designed and developed for self-hosted publishing by Automattic, Inc. The software is written in PHP and utilize either MySQL or MariaDB as a database, and is compatible with most web hosts. Wordpress includes a plugin architecture and a templating system that can be used to extend and customize your website. These are commonly known as WordPress plugins and WordPress themes and make up a whole open source and commercial eco-system where anyone is free to create products for the platform. 

Joomla is a free and open-source content management system written in PHP. The CMS is built entirely by volunteers from all over the world and has a strong community that provide educational resources, and extensions.