In my experience systems like Joomla and Drupal scare clients
Feature heavy CMS systems can intimidate clients who hesitate to learn and use them.
The 3 level deep Joomla menus can confuse even the most web-savy users.
This entirely defeats the purpose of building with a CMS.
You will spend more time walking clients through the endless Joomla menus, then it would have taken for you to make the changes in raw HTML yourself. Since the point of Content Management Systems is to allow clients to manage and update the content themselves, it doesn’t make sense to pick a system that non web-savy users are reluctant to use.
For most websites a simple wordpress based CMS works great.
The menus don’t intimidate clients
Simple WYSIWYG editor makes content changes easy.
Themes are easy to design and build
Plugins are easy to install and use
But for certain solutions joomla/drupal are better suited, such as:
Extensible User Profiles: for membership sites and portals
Modifiying the Back-end: messing with the wordpress core is not recommended
E-Commerce: plugins exist but wordpress, just doesn’t perform as well as a dedicated cart system
In conclusion your clients and their needs will determine which CMS platform to use.
So pick a CMS that your clients will use without need for handholding.