16.04 LTS Python 3.6.x
CAVEAT I use compiled from the source OpenCV for my needs. I you can work inside the world of precompiled packages this opinion can be irrelevant to you
- About Ubuntu 18.04. I’m not recommend to use 18.04, you’ll face in dependences hell.
- About Python 3.7. I had problems with libs, I would have waited while all underling libraries will start to support it before switching to it. Currently one will got a lot of headache and no benefits from 3.7.
- About Windows. IMO it’s a bad idea to use it. If you will need to compile something from source you’ll enter in the house of pain