Hi There, I think you will find OctoberCMS helpful also. It’s easy to get started even for a designer like me but you can have the developers set up the basics and easily maintain and extend it to suit your needs.
It’s open source
It’s easy to get started
Good documentation available
You get full control of the HTML and CSS you want to use
It’s built on top of the awesome Laravel PHP framework
You get some awesome plugins to add functionality like User management, WYSIWYG editors, etc.
It can be used for e-commerce
It’s built with PHP so you will need a server running PHP
I have been watching this great video series, and recommend it if you want to start with OctoberCMS: http://watch-learn.com/series/making-websites-with-october-cms