The reason its a 9 not a ten? the back end can be a little slow at times, and this is unfair, because for the backend to be so amazing, it has to do a huge amount of work!
concrete5 is a free and open source PHP built content management system for content on the web and also for intranets. Its emphasis is on management and editing with minimal technical skills and with an embedded editor allows most editing to be done directly from a page, rather than through an entirely separate interface or editor. It features integrated server caching, supports OpenID, version control, and SEO. As with most open source content management systems, its content management functionality can be augmented with many possible addons or via the developer API.
Online magazines and newspapers are the ideal target of concrete5's capabilities though many other sites can be made and managed as well. concrete5 is touted as being both developer and DIY friendly. Marketplace content to extend features are both free and not free, so cost of implementation will vary.