I don't have a huge pile of experience with Wordpress, but it seems reasonably straightforward. I gather that, while you have to write themes, it's pretty straightforward and you get a good deal of control.
I do know that, for the love of sweet zombie Jesus, do not even think about touching Typo3
. It's a very Enterprisey
open-source CMS that I had the misfortune to use once; it's thoroughly insane.
If Wordpress doesn't work out for you, the only other open-source CMS I hear about in anything other than pejorative terms is Drupal
. It's still big and complicated though, definitely try Wordpress first.
The bad news is that both Drupal and Wordpress (and Typo3, for that matter) are written in PHP. Stupid PHP.