I currently use Wordpress, not as a blogging application but for CMS. I’ve used ExpressionEngine in the past and I liked it very much, however I switched back to Wordpress because it was free and had lots of plugins available.
One advantage EE had over WP is the custom field tags, which Wordpress doesn’t have out of the box (it does but not very flexible unless you add a plugin that extends it) and it’s a little more confusing/difficult to use than EE. However, once I found a good plugin, I was able to do most things EE was able to do.
One major advantage I see over EE is the markup is much cleaner than EE and it is flexible in a way that you don’t have to have header/index/footer/sidebar required (although that is good practice WP forces you to use for ease of update.
I don’t think you need to know PHP to use WP either. Some basic crash course will help but other than the basic <?php ?> tags and function statements, WP documents the tags pretty well like any other CMS.
I’m just looking for major advantage to switch over to EE over WP.