I prefer something that you can build yourself so expo wasn't an option for me. Plus, I think most of the platforms one day (might be soon) will ban these services as they can deliver code to the app after it has been approved.

With Flutter it's super easy, they have a CLI that creates an initial boilerplate for your code that you can compile and deploy to your phone in just a single command with hot reload enabled. I guess it makes it easier even than expo as you don't have to scan anything on your phone :)