These are all my personal opinions, take it with a grain of salt. Having said that, here we go:
* Authentication - it is a pain if you'd like to deviate from the standard Django User model (using username to login instead of an email). I don't like Devise either.
* Asset pipeline, even though it is not updated anymore (sprockets) and partially replaced by webpacker is still better in Rails
* Configuration in multiple files, by environment, instead of a single config.py file
* Sidekiq has a better API compared to Celery. Also, Celery's default broker is RabbitMQ, not Redis. It is really hard to find managed RabbitMQ hosting, for Redis there are plenty
* Mailer previews, small but quite useful utility
* Testing - Minitest and Capybara is just a joy to work with
* I prefer ActiveRecord over Django ORM
I could go on and on, but I remember struggling a lot with Django/Celery when building a SaaS app. I decided to switch to Rails and haven't looked back (Rails has its warts as well). YMMV
What don't you like about it?
I decided to roll my own auth, but was very cognizant about the risks of going down this route. I used primitives provided by Rails (has_secure_password, has_secure_token) and made sure that my implementation is not susceptible to known exploits, such as session fixation attack: https://guides.rubyonrails.org/security.html#session-fixatio...
What have you needed to do that isn’t well supported by devise?