In Sass, I like
* clear separation of mixins and classes syntax.
* of course, @extend.
* partials naming convention separation from normal compiled sass files.
* been with Sass for a while and I'm way too comfortable with it.
Edit: Pre-mature submission earlier. Added few reasons why I like Sass.
LESS is inspired by Sass. Sass was designed to both simplify and extend CSS, so things like curly braces were removed from the syntax. LESS was designed to be as close to CSS as possible, so the syntax is identical to existing CSS code. As a result, existing CSS can be used as valid LESS code.
The newer versions of Sass also introduced a CSS-like syntax called SCSS (Sassy CSS).
I'd say they both allow writing dirtier CSS with a clean source code, the ease of nesting & mixin can blow up the size and complexity of the generated style without it being immediately visible.
> in a programming construct instead of static rules.
Most of what less and sass do are static expansion rules.
as a node developer, i am guaranteed to have a working node install. I don't need to integrate and managing a working ruby install into my production/deployment pipeline.
If you're looking for a simple setup that will allow you to use SCSS I can't recommend middleman enough, it's easy to setup and you can use livereload with it very easily (admittedly it does require ruby...). If you're on github you can even get free hosting using middleman-gh-pages.
Here you'll find more comprehensive comparison between the three of them: http://net.tutsplus.com/tutorials/html-css-techniques/sass-v...
Or I might think you are talking about browsing text files..