Which html&css preprocessors to choose?

Question

Preprocessors

The boy has grown up, and now it has become mandatory for him to study preprocessors. In short, what would you advise to choose from this:
Jade
Sass
Less
Emmet
(I know, they perform different tasks, if not difficult, write the differences - otherwise, on the Internet, I think there is a lot of information about them)
And most importantly:
What preprocessors do you use?? Why are you using them. Thanks

Answer 1

sass(scss) - as the most powerful. however, like the rest, it has its problems. The most unpleasant thing is the lack of a built-in option for resolving url (critical when building with webpack, in this case it is better to take a stylus).
I don't accept Jade/Pug because of the indentation based syntax, I prefer more html templating engines (twig, handlebars)
Emmet is now built into all more or less decent editors and IDEs by default.
upd I
forgot the main thing =)
It doesn't matter what exactly you choose. The important thing is that you learn how to use these tools in your work. And to one degree or another, you have to know everything. You never know what you'll have to work with.