In 2007 I was tasked to do some work on school district websites. I spent many hours evaluating publishing software and realized that WordPress actually lived up to the 5 minute install claims. That and the fact that you can train people in under an hour how to maintain their website/blog for their school or department made it the winner over many other choices.
Have a look at the infographic below on the Power of WordPress. You’ll see just how many others use it as well and why.