I always suggest Wordpress. It is by far the largest, so it has a monstrous community behind it that is always cranking out new plug-ins and themes if you decide you want to use one that is pre-made.
It is targeted to bloggers, but just like the others, it can be built from the ground up as whatever you want it to be. It uses the standard PHP with an SQL back end, so no surprises there. I have made several themes for Wordpress and the process is fairly painless so long as you have a reasonable comfort level with PHP.
Basically any well known CMS will work for you, but I figure if you are going to use one, you might as well use the one with the most support.