Having only dabbled in both, I am not an authority on either to share my opinion. From a fact's perspective, PowerShell provides a shell scripting environment whereas Python is an interpreted high-level programming language. Both can accomplish similar tasks but thier differences also help distinguish themselves to complete certain tasks.
So why not use both?
This was a question I began to research for this post and thought it would be an innovative idea to compare the similarities in syntax between Python and PowerShell. In conducting said research I came across the work of Adam Driscoll, an 8-year MVP in the Cloud and Datacenter space.