Everett Griffiths recently wrote a comparison between WordPress and MODx over at TipsFor.US. In the article he walks the reader through various CMS comparison factors such as installation, templating, menus, plugins, architecture, custom content, security, and support. This comparison specifically focuses on WordPress 3.1 and MODx Revolution.
Everett writes:
There are a lot of Content Management Systems (CMS’s) out there, so I wanted to give a blow-by-blow analysis comparing two of them: MODx and WordPress. I feel oddly qualified to do so: Brian and I just authored a book on WordPress plugin plugin development (WordPress 3 Plugin Development), and I am a MODx Solution Partner who was invited to speak at the MODxpo conference in Dallas last year. I’ve used both flavors of MODx (Evolution and Revolution) and WordPress while building somewhere around 50 web sites over the past couple years, and I like both systems. I have even contributed a couple plugins for both systems (e.g. Custom Content Type Manager for WordPress). So after the urging of some friends and colleagues (like Kris), I’m organizing my techno-ramblings into a coherent article.
This articles is a fair comparison between WordPress and MODx. If you're interested in reading the details of the article you should read the original article, WordPress vs. MODx, at the TipsFor.US site.