MODX

MODX is a PHP-based open-source CMS that's been solid since 2005. It gives you a flexible content structure through its element-based model and a powerful template engine. You have full control over your data structure and markup, which appeals to developers who want to avoid rigid templates and boilerplate.

MODX works best for custom publishing sites where you need non-standard content types or workflows. It's mature enough for production sites but requires more hands-on setup than managed platforms. Developers like it for its extensibility and lack of enforced conventions.