You should go with Python 3.
Python 2 is reaching it's end of life, and is no longer under active development.
Python 3 is the replacement for python 2, and it brings many improvement, including, but not limited to: syntax, run-time, etc.
Which version you ought to use is mostly dependent on what you want to get done.
If you can do exactly what you want with Python 3.x, great! There are a few minor downsides, such as very slightly worse library support and the fact that some current Linux distributions and Macs are still using 2.x as default (although Python 3 ships with many of them), but as a language Python 3.x is definitely ready. As long as Python 3.x is installed on your user's computers (which ought to be easy, since many people reading this may only be developing something for themselves or an environment they control) and you're writing things where you know none of the Python 2.x modules are needed, it is an excellent choice.
Python 2 will cease updates in 2020. Treat it as if it were already gone if you care anything about support for your projects. Python 3.6, as of this writing, is the most current and widely supported version thus far.
Python 2.7 have a great code base as examples, and for newbie, it is very easy to understand, why your code is not running as intended. Also, on small, educational and easy projects you will not see any differences with 3.1 (3.2) version. So it is my way. I'll also learning Python now, and 2.7 is my choice. So when you will see, where is 2.7 is not enough for current code, you already will know how to switch to the 3
it is better to learn python 3....there are little things which are different between python 2and 3
and as python 2is ending its life as our friend said
so it is better to work with python 3 from first ...u know ... and some features r improved in python 3