What CMS is a pleasure to work with as a developer?
I use wagtail on all of my projects and it is amazing to work with:
Streamfield is how I think more CMS's will go in the future. It's basically building blocks (that you make as a dev) that allow you to create every page to be unique in layout, content, etc.
Only caveat is that it wants to handle a lot of the URLs for you (I guess what CMS doesn't) so if you have anything else custom going on in your Django app need to be aware of that.
I'm enjoying TakeShape.io so far in my project. There's not a lot of documentation aside from that they've written and there are no widgets like the ones you'd find in Wordpress or others. Depends on what you're looking for!
If we're specifically talking about as a developer and only a developer then Jekyll. It's my default for all my own sites / blogs.