disclaimer - I'm a Swift developer and I'm asking this for Data Scientists who are interested in Core ML
A Google search has given mixed results, some pages say that CoreML only supports Python 2.7, some say that it has some support for Python 3 but works much better on Python 2.7, and others say it works on 3 just as well as 2. What is the current answer for this?
Core ML doesn't support Python at all, as it's the API for doing inference on iOS and macOS devices. It's written in Obj-C and C++ and has an Obj-C and Swift API.
coremltools, which is a Python package for building Core ML models and for converting them from other tools such as TensorFlow, works both on Python 2.7 and Python 3.x.
(It used to work only with Python 2, but that was fixed several years ago. Since Python 2 is deprecated, you should really use it with Python 3.)