[spohlenz]

It's not open-source, but Wheelhouse (https://www.wheelhousecms.com/) is my answer to not being able to find a CMS I could enjoy working with.

It's Ruby on Rails based, so that power is always there when you need, but it then adds a flexible templating system for generation of content-editable fields (example here: https://www.wheelhousecms.com/blog/2011/8/flexible-templates...).