Have used Drupal, Joomla (back when it was called mambo), Typo3 and Wordpress. Drupal rocks for small to mid sized sites. The learning curve can make your head spin, but buy the pro drupal development book and give yourself a weekend to get yourself in a better place. (if you already know PHP). Very well thought out software, once you get the hang of it - it is truly amazing what you can do in a few days. The closest thing to a meta-programming language that I have seen in the CMS world. 0 to 60 is really slow, but once you've done 0 to 60 once, 0 to 100 is delightfully easy. Wordpress is very elegant, but don't make the mistake of thinking that it is a CMS. It is blogging software. FANTASTIC blogging software, mediocre CMS for anything but blogging. You go 0 to 30 out of the box without thinking, but getting to 60 mph is hard and if you ever even think of going to 100 you'll hate the stuff. Joomla/Mambo - I haven't used it in years, but when i did use it I was stuck scratching my head often at "why can't I do xxxx" or "why would you do it that way." You go 0 to 60 faster, but from 60 to 100 you will feel the bumps in the road. Typo3 - I haven't got under the hood much with Typo3. It is probably the most convoluted of the four because they maintain reverse compatibility. I don't see any reason to choose it. For me, unless it is a blog, Drupal wins. If you invest the time into learning it, you won't regret it. I love drupal, but it does have two prominent downsides - 1) dearth of good themes 2) because it has so many options and is so flexible it can be resource intensive/not scale effortlessly. That said you can overcome these problems.
Joomla has a huge community behind it with all the right add-ons to make development simple. Go with wordpress if you plan on blogging at all.
If you are not a PHP programmer and looking for a CMS that's easy to design for, TYPO3 is a great option. The main reason I stuck with TYPO3 was the powerful configuration language called TypoScript which, more me, was faster and easier to learn than PHP. I'm not a programmer naturally. The platform also offers a lot of nice plugins. TYPO3 simply has not caught on in the USA like it has Europe. Larger European TYPO3 companies like http://www.aoemedia.com make the strongest case for taking a closer look at TYPO3. Their references are pretty impressive too.
There are tons of solid ones.. example here: http://cmstester.com/list-of-cms-software/ but it really depends on what you are looking for. I find silverstripe, cms made simple and others to be quite good as well. While drupal, joomla and wordpress seem to be the most popular. Here are some review links I did.. perhaps they can help: http://cmstester.com/wordpress-2-5-1-review/ http://cmstester.com/drupal-6-2-review/ http://cmstester.com/joomla-1-5-2-review/
Joomla is the best. Never used wordpress. If you know a bit about programming the Joomla can make miracles
Do you need an understanding of developing though, like understanding php or anything? is it more advanced and not for someone used to wordpress?