Many website content management system (CMS) solutions have evolved into robust, feature-rich and free/affordable online publishing systems. But they are not all the same, in fact, many aren't even playing in the same game. Choosing the right CMS by considering your current and future business requirements will ensure the solution you pick will serve you well for a long time.
As similar as the end product may be, there will usually be some kind of trade-off over the competing CMS solutions - these trade-offs are worth investigating.
The success of your CMS website depends on a lot of different variables. Unless you have a technical staff to support it, you may want a stable, secure solution that simply manages the content, not the CMS process itself.
Unless you need a complicated app or process development, you may want to stay clear of CMS solutions like Joomla and Drupal, they may be considerably more than you need. Wordpress will get you up and be running in almost no time at all, but customization requirements could be cost-prohibitive. ExpressionEngine site development will take a little longer to implement, but it's basically free of the CMS constraints and allows for total design and development freedom (and as of November it is free open source).