Not sure how far to expand this, but here are some links to read:
I like Anaconda https://www.anaconda.com/distribution/ as it “just works” for my multiple Python environments, and for R and comes pre-installed with a lot of the stuff I want–saving me hassle. As described above, I have multiple Anaconda environments Python2 for my “production”, and “Python3” for my project to migrate the Python2 app into Python3. I also have an “R” environment that I play with. All environments are completely independent of MacOS’s version of Python which I leave alone.
It’s really bad form to install updates or changes to Mac OSX’s version of Python. Leave it alone!
I have used virtualenv https://virtualenv.pypa.io/en/latest/ and have no problem with it. Just found Anaconda easier to explain to my colleagues and successors.