Dynamics 365 Workflow vs Microsoft Flow – Which one do I use?

I keep hearing the same question over and over again. And I keep seeing long drawn out answers to the question, sometimes with it being explained with a half dozen bullet points. Other times, with unnecessary examples. I have been guilty of it myself.

What’s the question?

When should I use Microsoft Flow vs Dynamics 365 Workflow to do ‘something’?

Here is the simple, complete and succinct answer.

Assume for a moment that Microsoft Flow didn’t exist. Can you do what you need to do in CRM with the built-in workflow engine? If so, do it with Workflow. Otherwise look to Microsoft Flow.

End of subject. End of debate.