Simplest answer to a not so simple question, and strictly in my own opinion, is Ruby. For someone coming from Python, you’ll find the syntax nearly identical.
However, despite the attractiveness of choosing one based on ease of learning, I don’t think that should be your main motivation.
I love Ruby. It’s elegant, simple and powerful. It’s used mostly on the server side, but offers front-end features like ERB, given a framework like Sinatra or Rails. Not to mention, there is a ton of Gems that can help achieve most tasks.
You can do so much more with it. There’s an endless amount of libraries and frameworks that’ll help achieve anything. From adding some bling and interactions to a boring web page, to visualizing data and even a fully configured application. You can run it pretty much anywhere, browser, server, or even native with new libraries like React, and Vue.
Basically, deciding what your goals are, will help direct you to the right one. I say why one over the other? The more the merrier