SASS is quite good but stylus has more features. SASS's bigger community is surely a point in its favor but stylus's simple excellence makes it the victor for me.

Stylus seems strictly better from my narrow perspective. 0 negatives, about 6 positives the other 2 miss.

why exclude Stylus?

I dislike Stylus specifically because of its optional syntax - permitting a bunch of different syntax variants within the same file seems like it's asking for disaster in a team environment.

Sass strikes a great balance between terse and consistent, which I really appreciate.

Great question. I'd like to know too considering I have experience with both SASS and LESS but not Stylus.

Did you happen to see the link to the Stylus Viewpoint? http://www.slant.co/topics/217/viewpoints/1/~best-css-prepro...

I wonder about this as well. The description of Stylus is very appropriate and it's well known that Stylus provides a more powerful feature set than both LESS and SASS as well as optional syntax that makes it easier to integrate into your workflow, IMO.

The community might not be as big as the SASS, but I love using Roots CSS for all my Node projects.

glad you're enjoying it! feel free to reach out and/or contribute any time <3

ref: http://roots.cx/axis