I know Javascript is fast but...
I cannot go with such a messy ecosystem. I find Python highly preferrable for my backend code for more or less low and middle traffic stuff.
I know Python is not that good deployment-wise, but the language is really understandable, I have tools for every use case, I can easily provide bindings from C++ code and it is a joy to work with.
If on top of that, they keep increasing its performance, I think I will stick to it for lots of backend tasks (except for high performance, where I have lately been doing with C++ and Capnproto RPC for distributed stuff).
It comes down to language preferences. I find Python to be the worst thing computer science has to offer. No nested scoping in functions, variables leak through branches and loops due to lack of scopes, no classic for loops, but worst of all, installing python packages and frameworks never ever goes smoothly.
I would like to love Jupyter notebooks because Notebooks are great for prototyping, but Jupyter and Python plotting libs are so clunky and slow, I always have to fall back to Node or writing a web page with JS and svg for plotting and prototyping.