Wordpress has the easiest editor for adding blog posts - but on any website that isn't a blog, it can be difficult to get good layout of the content through the wordpress editor. The problem with most other forms of CMS, is how well they work with the stylesheets of the site itself. Usually this integration is reasonably poor at best. If anyone knows of one that works very well with the CSS - please let me know!
Wordpress all the way, I don't care what level you are at... or what application (except maybe article or web site directory, but even then)