Joomla is the best CMS. If you are worry about security then Paid would be right choice but as you described freeware then move forward to free available CMS. PHP is open source so you can go for secure server and also search some security tool over internet which may help you to protect your custom build work.
Paid and Free CMS's are just as good as one another. It all boils down to how the administrator sets it up.
nancysmith is right. Joomla is arguably the best CMS around.
I personally find Drupal easier to handle and GetSimple to be light fast and free (good for practice).
When it comes to modules, I'm guessing that the free ones have the most choices.
Drupal, Joomla and Wordpress are very popular. And itís better to try them to find out which of them is the best for, I like wordpress and drupal is a very good one. As for me I use CMS dotEditor, it has everything I need and I really like it in comparison with other systems. But of course this question of a taste and money)
Wordpress can be used to do just about anything you can dream of.
Sajan Parikh - PHP Development | Server Management | Linux Administration | Web Consulting Feel free to get in touch with me if I can be of assistance with anything.
e: [email protected] | w: sajan.io
Give me a call at (563) 447-0995.