Just a quick follow-up
I've developed using both Drupal and Joomla, in the early days Wordpress was primarily for blogging and it didn't offer ME the flexibily to be as creative as I wanted (I know it's much improved now) so I did not go there.
C5 has a lot to offer both the developer and a user who wants to maintain their own site without developers involvement. It is by far (IMHO) the easiest to use. I'm a webmaster and if I can pass on most of the CMS editing to my users with out them turning the website into a "colouring book" and/or screwing things up then I'm really happy.
I have two types of users - ones who want to just update the sites content and ones who one to dabble on being creative (web designer wannabes).
C5 offers both, as well you can secure design areas (Headers, footers, banners etc) so users can only update the blocks they need to without screwing up the whole site. For the would be user/designer, simple sites can be up quickly and the editing and feature functions are for the most part intuitive.
The C5 Community is very active. There are add-ons galore (paid for and free) that can be downloaded from a user market place. I've also found that the support communiity is very active, informative and attentitve. Most questions that I have asked have had good responses within hours with proper assistance and/or good intructions/directions.
I've developed C5 sites for small biz (simple 5 pages sites with - Home, About Us, Services/Products, Contact Us) and more sophistcated sites as well as "club/organization sites" with user login, registration and privacy areas which are now managed by the users themselves. I get called upon to develop add ons or provide some guidance once live but for the most part they have got the ball - and are happy.
I'm happy with C5 - although a this time of writing, DH's one-click install for C5 is missing from their OCI panesl. Just as I was going to set up another mock up for a user.