Most people use Jupyter Notebook for Iterative Programming and keep Code, Results visualizations and Documentations together. Once the experimentation is done, you may want to abstract things into functions and put into .py file. Jupyter Notebooks are still relevant even when doing large projects to experiment. This is what you will see in Fast.AI, where all the library code is in .py file, but the lessons are in jupyter notebook.
There’s no right answer to what’s the best Text Editor for Python files - Jupyter, Vim, SublimeText, Atom, PyCharm,and many more. This is more like asking what’s your favorite food and let me see if that’s also something I like. The only way to evaluate is to try a few of them and see what’s your Taste 