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