When comparing Stylecow vs cssnext, the Slant community recommends cssnext for most people. In the question“What are the best CSS preprocessors/postprocessors?” cssnext is ranked 5th while Stylecow is ranked 7th. The most important reason people chose cssnext is:
cssnext is a PostCSS plugin, which makes it pretty easy to use for people who are already using PostCSS.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Easy to install and use
It's written in node, so you can install it with npm. All available plugins are installed by default and include some development tools like a watcher and a browser live-reload so it don't need more than few seconds to be ready to start to work.
Pro Advanced API and parser
The parser detects any CSS syntax error found. The output code can be customized to follow your own code style rules (indentation, spaces, string quotes, etc). It has a clean and powerfull API, which make easy to create new plugins.
Pro No need to learn a new syntax
Since Stylecow allows developers to write simple, vanilla CSS, there's no need to learn a whole new language.
Pro Built on PostCSS
cssnext is a PostCSS plugin, which makes it pretty easy to use for people who are already using PostCSS.
Pro JavaScript-based
Because the parser/compiler can function in a web browser, it can be used with systems that cannot run similar technology on the server. For example, you could build a WordPress plugin with a front-end application that transforms CSS.
Pro No need to learn a new syntax
Since css-next only adds new CSS features in a way that all browsers can support it, it's still CSS. So there's no need to learn any new syntax.
Cons
Con May be merged with PostCSS in the future
Since Stylecow is pretty small and hasn't gained a lot of traction in the past 5 or so years since it was first released but also because it serves kind of the same purpose as PostCSS which is much more popular, there have been discussions on merging the two projects together.
Con Small community
Stylecow doesn't have a very large community. This can make it difficult to find answers and increases the risk of the project being abandoned.
Con Lack of support in IDEs
Currently there is very little support for syntax highlighting when writing PostCSS plugins.