Now I use Julia most of the time. It's great, not just for the speed. The combination of the type system and multiple dispatch lead to much better implementations. I find the same implementations take less code and are easier to understand. Also using a language without a native array type for data science work always seemed crazy to me. There are also a number of smaller things about Julia that are nice compared to Python and reduce friction for me (broadcast a function fn(...) withfn.(...), much better/cleaner package management than Python). I still have to use Python for a lot of work but I'm hoping more people try Julia so that the Python hedgemony can end.