SASS vs. LESS vs. Stylus.
What's the better stylesheets language?

I always wrote plain CSS. But like a week ago, I decided to try scss. Not a huge difference but it has nice features.

i was in love with stylus but it's so tempting to change the css output by hand. Which results that the transpiler stops working 😆

But since there are css custom properties ( css variables ), i don't use these anymore.

https://goo.gl/axaVT
Using CSS custom properties (variables) - CSS: Cascading Style ...

dont know about LESS, SASS is nice and lets me nest classes so i can write BEM effortlessly, same with stylus and PostCSS. Stylus sometimes throws errors if indented with spaces instead of tabs or vice versa, depends how you configure it, so it breaks at compile time. My list is: PostCSS, SASS, Stylus, LESS.

Currently trying JSS, seems promising for web apps for now

SCSS

Css by itself is fine to me although i do enjoy sass and less.

Plain CSS or SCSS. Personally mixin' all the things.

Scss, especially for the nesting. I like it better than sass because css is valid scss but not valid sass.

Try stylus you won't look back

Tried all of them (but I'm a backend grill) and i hightly prefer sass. Then it's your choice