Wanting to "Learn game development" is very, very vague.
If you want to develop your own, small games, for fun, while learning how to structure the application, go with python.
If you want to learn more hard-core graphics programming, or gain experience towards working in the industry, I would have to say go with c++.
I think the answer depends very much on your current skillset and goals. Note that I'm certainly no expert in the field.
