My vote goes to WordPress. I've been using it for 2 years now and don't intend on ever using anything else. I've tried out a few other CMS scripts, but in my own opinion, nothing came close to the ease of use and customization of WordPress. WP is extremely easy to customize with its flexible plugin and theme system.
All the websites I create that require a CMS have WordPress installed.
JOOMLA. Joomla has the ability to create a full blown site that has shopping carts and anything else you want to create. Yes it has points in which you will need more knowledge of html, php, css and other coding but there is a large community out there to help both free and paid.
I integrate, use and work closely with CushyCMS for all my clients who request a CMS if they are not using Joomla or Mambo, etc. CushyCMS is a free WYSIWYG Content Management System. It is amazing, and worth the checkout.