Best open source CMS for developers to customize and add dynamic pages and content [closed]

Two highly versatile and configurable CMSs I have used:

• Wolf CMS - PHP-based, makes PHP directly accessible in backend; "templating" is simply (X)HTML + CSS + PHP calls for content; highly extensible.
• Symphony CMS - XML + PHP based; XSLT makes it possible to manipulate site content in creative ways.

So, neither Python-based, and Symphony requires getting up to speed with XML/XSLT. Both tick all your boxes and put a fair bit of power into developer's hands.

+1 for mezzanine. I have done quite a bit of work with mezzanine and you can have custom templates on a per slug basis http://mezzanine.jupo.org/docs/content-architecture.html#page-templates and add special logic through page processors http://mezzanine.jupo.org/docs/content-architecture.html#page-processors (You can specify page processors on a per slug basis or to apply to all models of a certain type which inherit from Mezzanine's Page).

What this means is you could go into the admin, create a page called random page, and then create a template called random-page.html and random page will be rendered using your new template rather than the default. You could also create a file called page_processors.py, use a decorator giving it the slug random-page and write custom code implementing form processing or whatever.

In my experience it is very extensible and quite easy to work with and understand as well as having good docs at mezzanine.jupo.org/docs

my 2 cents

Cake php is nice php framework which you can quickly use build a custom CMS. It is also quite similar to django in its setup. An added bonus with it is that it has caching implemented from the start. It uses a MVC structure, so it very easy to get your head around.

If you know and are comfortable using django then why not stick with that? as django is perfect for all your requirements.