If there is one technology, framework, programming language, paradigm, ... you would recommend another dev to learn right now, what would it be?
Why do you recommend it?
What are the benefits for somebody learning it, in contrast to other technologies?
I often recommend Elastic, because it's an amazing, simple to learn, install, and configure two-for-one deal, where you get an amazing search engine, and a powerful analytics product combined.
However, it's resource footprint is not trivial! But I suppose that's the price of greatness.