Hey, I was using LESS for quite some time and switchted now to Sass. For me both are at a pretty same level.

And yeah, I actually can't think of a time before preprocessors. Splitting style components into different files, so you have everything organized. Components, forms, layouts, media stuff, icons and so on.

Variables are a huge advantage, extending existing classes, so you minimize redundant styles and mixins. I mean they just safe the day. You can make complex mixins like svg backgrounds with png fallback and retina support and then just use them like @include svg-background(my-awesome-image);

And there are some "frameworks" with various mixins like lesshat or bourbon for sass.

If you working with task runners like gulp or grunt you setup your file once and you're fine.

I've used LESS quite extensively for a big development project. It works really well, especially combined with Grunt.

We have a set of site-wide .less files - chrome, forms, components, etc - then a .less file per template.

We use Grunt to convert these to CSS, combine and minify to a single style.min.css.

I've heard good things about SASS, and it seems that many people think it's superior - but we're quite far in with LESS, so haven't seriously compared the two.

Hello. I use a less known css processor: stylecow (I'm one of the creators). The most important points:

• It allows to write pure css (instead a pseudo-language such less or sass).
• It has development tools like watcher, browser live-reload, grunt/gulp plugins, etc.
• It's very fast, customizable with plugins and fix the code automatically (adding vendor prefixes, polyfills, etc) to work fine in all browsers.
• It allows to use variables, nested rules, placeholders, color manipulation, etc, but using the w3c standard syntax