I've used Mambo and Joomla in the past and they've been very good, loads of add-ons, intuitive to use.

I even tried a little-known one called E107 which is actually really good ... it has some really cool add-ons.

However, for CMS I just don't think you can beat a server installed Wordpress ... it's easy to install in cpanel, there's a tonne of support for it and and the add-on support is incredible.

Think of something that you want it to do, and there's bound to be an add-on for it :-)

If you're not good at the teccie stuff Siteground specialize in installing and supporting CMS installations on packages like Joomla, Wordpress, Mambo, Drupal, they provide some great free tutorials and also give decent free templates as well.