I personally favor Mambo over phpNuke. But nothing serves you better than you serve yourself. Create one of your own. It's not hard, it's just time consuming. The pluses are that you can make it how you want, and you don't have to worry about copyright and legal crap of what you can and can't remove.
As far as I know, phpNuke now requires you to pay like $10 (USD) to download it, complete 6u╙sh!t!!
But there are many out there:
Mambo Open Source
Geeklog
PostNuke
phpNuke
Drupal
phpWCMS
phpWebsite
SiteFrame
Xoops
Typo3
That's just what's on Fantastico (cPanel extension).
OpenSource CMS
Nucleus CMS
Plone
But to do a comparison, go here:
CMS Matrix
~Brett
