Node is a safe investment of time, as it's shooting up. MEAN as a stack is pretty big right now, but it does require you to learn four new frameworks / concepts and Angular in particular isn't a one-weekend catch-up kind of undertaking (unless you already do know any of these?).
I think Samuel is right in that any server-side technology will help you along the way. But be aware that the server world is being shaken up dramatically these days, by containers and devops tooling etc... Simply knowing your way around a Linux or Windows server OS isn't going to cut it for much longer.
Node is well-placed to handle these new trends, as is Python btw.
Edit: Meteor.js is a great entry point for getting into a single full-stack framework. Especially if you go with the just replaced version 1.2, in which you don't have to worry about importing anything, wondering about folder structure or such things. It's all taken care of for you, and their front-end templating system (Blaze) is baby-play easy.
Careful with the latest version (v1.3), though: While the above all still works in 1.3, it's now deprecated in favor of explicit modularization and "proper" view layers such as React and Angular, discouraging the ease of entry that was the default in v1.2.