Sass vs Stylus -- What do you use and why?

Sass is Sass, my shop uses it because it's well supported and it's part of the toolset we started building with. We've messed around with Stylus for some projects and didn't have complaints but ultimately we've hewed towards Sass for inertial reasons.

We're now seeing some functionality in Stylus that Sass doesn't have (property lookup for example) that's attractive. For those out there who use either or both what do you prefer, why, and does either look to have a brighter future from where your sitting?