As far as I'm concerned, Less, Sass and Stylus all provide the features for the way I like to write styles (DRY, with composability) so the main thing that infl

As far as I'm concerned, Less, Sass and Stylus all provide the features for the way I like to write styles (DRY, with composability) so the main thing that influences which I'll use on a project is how easily it fits into the workflow. That means Stylus for Express projects, Sass for Python/Flask. When I'm at my day job I use Less (well, more specifically Lessphp) for the simple reason that there's a Drupal module for it, which integrates very well with building Drupal sites.