I learned Python more than 10 years ago, but later chose Rails to be my first web framework to learn, as I also wanted to learn more about Ruby, hence the question.
* I've always preferred Python over Ruby. Explicit imports, namespaces and the "only one way to do something" philosophy have felt more scalable. In general the language does not promote as much implicit magic
* Django reflects the same philosophy: more explicit definitions, a slight bit more configuration and ceremony but easier debuggability.
* The Django docs are, to me, some of the best there is in documenting the framework extensively but also teaching good practices. I've always felt the Ruby docs to be lacking in the latter department so you see more drift in Ruby projects on how to approach the same problems
* Django has felt much stable over the years. Migration between major versions is a breeze.
* The Python library ecosystem is much larger
* The Django admin and Rest Framework are some of the biggest timesavers I've seen. Rails has similar projects but they don't quite make it
Unless you're doing a GIS or project with scientific computing I would not let these factors go above personal preference, as Rails is still an excellent framework.