Out of curiosity, in what ways is Zurb superior to Bootstrap? I immediately see that they use Sass rather than Less. That's a smart move I appreciate. Anything

Out of curiosity, in what ways is Zurb superior to Bootstrap? I immediately see that they use Sass rather than Less. That's a smart move I appreciate. Anything else? Better licensing, browser support, toolset? I think it looks great but I'd also like to have a good reason to suggest to a developer whether to use one or the other.