Listed in order of preference. After wordpress and perch i would learn Drupal and after Code Igniter.

Editing Content (very simple websites)

1. Perch
2. Pulse CMS (Open Source, no database, no image upload feature)
3. Unify
4. CushyCMS (Hosted)

Blogs, Traditional simpler websites

1. WordPress
2. Subreamer (have to pay)

Websites with some extra features

1. Joomla

Advanced CMS with framework capabilities

1. Drupal

Frameworks

1. Code Igniter (best for beginners and getting things done)
2. Kohana (better design and PHP5 when compared to codeigniter, but not so well documented)
3. CakePHP