Which python web framework do I use - Flask or Django?

Let me take you on a beautiful journey.

Flask:
 
You start to ride a bike.
Being a noob you mess up a lot of times.
And, get hurt over and over.
You learn things now.

Django:

You start to ride a bike.
But, a plot twist.
You learn riding a bike by observing others.
You sit on their back and see how much smoothly they do ride.

Now, either situations are possible:

• You copy them flawlessly and become a pro.
• You mess things up badly, end up injuring self and dumbstruck about how things are done.

Now the choice lies with you. You know your caliber better than anyone. 

Coming to the point, Flask and Django are both awesome in their own aspects.

Flask can help you learn and get the feel of how things are carried out in backend development and how frontend can be improved exponentially with a correct backend setup. And the learning curve is much gentle as compared to Django. But the problem lies in doing much on your own messes things up at large scale, hence slows down the production work. 

With Django, you can get yourself settled and ready for professional development, but if you are a beginner, you might end in messing the basics up and staying confused for a long time with the introduction of new concepts. Still, Django is fast and much more efficient in practical terms as compared to Flask anyday. It comes with a useful admin interface, bootstrapping tool, a robust ORM to work with widely used databases like MySQL, Oracle, SQLite and PostgreSQL. Also, the ORM system enables developers to perform common database operations without writing lengthy SQL queries. The built-in migrations tool is pretty useful.


Therefore I would suggest that if you are going to start web development with python, go with flask first, clear the basics first. 

By basics, I mean that you should be good enough to build your own CMS (blogs basically) as they quiet effective in checking your progress.
You should be familiar with words like migration, a bad request, modals, views and all sorts of stuff.

With that done you can surely start your way as a Django developer.
That would be easy to start then.
I also suffered from this confusion once but took the right choice by judging my caliber well!