Overview: Very flexible, evolving, and versatile. Easiest to develop small and large sites with great hierarchy, some temporary compatibility issues with browsers.
Main advantages include a quick and easy template system that allows the easiest creation of themes among the major platforms. Fast-paced development, minor releases include stability/security fixes as well as feature updates. ModX offers the most flexibility for page output. ModX is great for small and large sites.
Main disadvantages include an administrator interface based on ExtJS that can be subject to some occasional and temporary bugs or browser incompatibilities. Some features built in to other management systems aren’t included, although this is somewhat by design due to the flexibility offered.
Overview: Popular, lots of add-ons and long-term platform stability, less applicable for the smallest/simplest of sites.
Main advantages include popularity, great hosting support and user comfort, and an active development community. In addition, Drupal has the most add-on packages. User interaction is polished and intuitive.
Main disadvantages include a convoluted template system and complexity for developers. Content is managed through a giant cluster where you have to build your own menu. The advantage of this is flexibility. Radian Technical Marketing prefers a hierarchy of content that determines menu structure, which is what most management systems do.
Also, the pace of development is slow. Historically, there are 2-3 years between major updates. Some like having a stable working platform for years, while others prefer an evolving platform that gains more features.
Overview: scalable, powerful and robust with specific Plone hosting required.
Main advantages include scalability, user management and security. Out of the box it can scale up from small sites to large sites. For large (busy) sites, Plone facilitates an easier multi-server setup than other management systems. Also, Plone has nice features for implementing multi-language sites. The user/permission management (users, groups, permissions, multi-tiered access to resources, content workflow) capabilities are the most robust and flexible of any CMS. Regarding security, the Plone/Zope/Python combination has had fewer security flaws in recent years than Drupal/PHP, WordPress/PHP, and other major content management systems. Plone also has a large and active development community.
Main disadvantages include complexity and hosting. With the scalability and other nice features comes a certain learning curve for Plone development. A higher baseline for hosting requirements also comes with the scalability. Generally, Plone cannot be run on the inexpensive, shared hosting packages (from Network Solutions, GoDaddy, etc.). A VPS solution is usually required.
Overview: WordPress is a CMS based on PHP with a MySQL database. WordPress was originally built only as a platform for blogging, but has slowly developed into a full-featured CMS. All in all it is a good CMS with an excellent admin user interface that is popular, well supported, easy to use, with plenty of plugins to extend functionality for most needs.
The main advantages include an easy-to-use admin interface, which is well designed and powerful. Content management, site maintenance and upgrades are all very smooth. When there must be a tradeoff between extra features (and added complexity) vs. usability, WordPress usually chooses the most usable instead of the most complex.
Due to its popularity, especially as a blogging platform, it is well known by users and developers alike and well-supported by web hosts. There is a good development community with plenty of third-party plugins. The core product is stable and receives regular bug fix updates and several feature updates each year.
The main disadvantages with WordPress include growing pains from its blog to CMS history — theming is more difficult than it needs to be for developers. Probably due to its popularity, there are a lot of third-party plugins that offer some functionality free, trying to hook you in to buy the “premium” version for complete functionality. There are usually entirely free alternatives to this.