I am considering hippo
It need to have a debian/ubuntu friendly licence.
Thanks,
Hippo CMS is Apache licensed, so in that sense an option for you. If you want to get started, go to: http://www.onehippo.org/
I read that Liferay is one of the best open source Java-based portals. Also it's specifically designed be useful for enterprise use.
Also it's licensed under the MIT-License.
It all depends on your exact needs but without more details, I'd add Alfresco, Nuxeo and Exo to your list.