What is the best preprocessor for CSS?

Question

css

Good day!
Having mastered the layout, I faced the question of choosing preprocessors. Here I got confused. I'm not trying to ask stupid questions like "which is better?". Just those who use them, please explain which ones do you think are the most effective? About Sass and Bootstrap, I realized they are not indispensable. The answer will be enough for me - do I need to study any more, or not?
Thanks in advance!

Answer 1

Yes, there is not much difference here, sass is good because many css frameworks use it by default, and you can also look less.

Answer 2

IMHO Sass (SCSS) is already the de facto standard.

Answer 3

https://habrahabr.ru/post/144309/

Answer 4

О Sass и Bootstrap я понял, они не незаменимы.
why?
as an analogue of sass there is less, which, by the way, is more relevant if you use bootstrap
bootstrap is not a preprocessor at all and it has a bunch of analogues, which in turn use less or sass or both to choose from.

Answer 5

CSS Preprocessors