I use CMS's and blogs on a daily basis. My favourite CMS is most definitely Drupal, but i do find there built in blog lagging behind WordPress. WordPress out of the box is brilliant and it is so easy to use for the novice who doesnt have any technical knowledge. Being a Web Developer/ Designer, i find it extremely important that the end user (client) will be able to navigate and update their website easily and without my hassle. I find the backend of Drupal quite confusing for the end user and a number of clients have complained how difficult it is, to navigate around and make changes. The same can be said for the blog of Drupal.
It does have advantages:
Conclusion I prefer WordPress as a blog, and Drupal as a CMS. It is each to their own i think. If i design a site, i use both and get the best of both worlds.