Flask is fun and easy to setup, as it says on Flask website. And that's true. This microframework for Python offers a powerful way of annotating Python function with REST endpoint. I’m using Flask to publish ML model API to be accessible by the 3rd party business applications.
Another great way to create, deploy, and monetize your function as an API is by using www.byvalue.org . There you can easily create micro services from any set of functions, including ML models. Hope you check it out :)