I'm a 10th grader with a pretty comfortable understanding of Java. Should I learn Python or C++ next?

I'm on a time crunch so I'll be brief with my current reasoning

Python: I've recently become very interested in machine learning, which I hear the compactness of Python makes simple

C++: The only reason I'm considering learning C++ next is because my brothers roommate - a computer science major at USC - said I should do so. His reason behind this was simple -- from C++ you can transition to a wide variety of languages with ease.

However, considering both languages are heavily object oriented, is there really that large of a benifit in learning C++? To be it seems more beneficial to learn a language like Python or JavaScript which is web-based. I haven't been able to find any mind-changing info online, so I thought I'd ask here, putting forth my personal situation.