There is of course no such thing like a ‘best language for machine learning’ – but as a matter of fact Python is still Nr. 1 and increasing:
Image Source: https://stackoverflow.blog/2017/09/06/incredible-growth-python/
We use in all our courses Python due to the fact that it is an “industrial standard” and widely available. I would love e.g. Julia, which is much faster, but it remains rather academic and needs a lot of additional effort. It is not astonishing that Python is worldwide the most popular tool for machine learning and artificial intelligence as there are deep learning frameworks available, including Tensor Flow, Pandas, NumPy, PyBrain, Scikit, SimpleAI, EasyAI, etc. etc.
Consequently, in our courses we teach Python, have a look at:
Marcus D. Bloice & Andreas Holzinger 2016. A Tutorial on Machine Learning and Data Science Tools with Python. In: Holzinger, Andreas (ed.) Machine Learning for Health Informatics, Lecture Notes in Artificial Intelligence LNAI 9605. Heidelberg: Springer, pp. 437-483, doi:10.1007/978-3-319-50478-0_22. [link to paper]