Trionic Labs

SASS is a programmable approach to stylesheets which really adds some cool features. It can make a stylesheet easier to read, easier to update and also adds some powerful features like functions, variables and imports. (See http://sass-lang.com/docs/yardoc/file.SASS_REFERENCE.html for more details.)
This plugin enables any WordPress Theme to use SASS stylesheets. In a wordpress theme, the comments at the top of style.css are used to define the theme. For this reason, this plugin will not allow a .sass or .scss file named ‘style’.

WordPress SASS

This plugin provides automated SASS stylesheet generation.

Sebastian Echeverry

This plugin allows you to use SCSS files directly in wp_enqueue_style. Just add the file to the list of styles and the plugin will compile it when necessary.
The base of this plugin is strongly influenced by the <a href="https://wordpress.org/plugins/wp-scss/" rel="ugc">WP-SCSS</a> code and extracts some ideas from <a href="https://wordpress.org/plugins/sassify/" rel="ugc">Sassify</a>. The goal is to keep the plugin updated with the latest version of <a href="https://packagist.org/packages/scssphp/scssphp" rel="nofollow ugc">scssphp</a>, remove configuration options from the graphical interface, and use the scssphp capabilities to create debug files.
This plugin is not intended to be installed by a conventional user, but to be required by templates or plugins that wish to include SCSS style files and therefore the configuration is expected to be done in the code.

SCSS-Library

Add support for using SCSS style files with wp_enqueue_style.

WordPress SASS vs SCSS-Library