I've been using the Julia language for around 5 years now, and I've grown rather fond of it. By now, I can't really imagine how to do the things I'm doing in any other language. This could, of course, be a misconception and the result of not knowing any other language well enough - a form of the Dunning–Kruger effect. But my impression is that Julia is the best language to write high performance numeric libraries for machine learning, data science, solvers, optimizations, etc....