SitePoint (www.sitepoint.com) is one of the great sources of information on WordPress and other web design topics. They posted an article on the best current design frameworks (www.sitepoint.com/best-web-designing-frameworks-2014/), and listed these frameworks:

Not mentioned in the article was Headway Themes (headwaythemes.com), which I came across recently. This appears to be a really great tool, a WYSIWYG drag-n-drop tool for creating your own web design, based on a grid system or a block system. Full WP integration, including Buddy Press, MultiUser, Woo Commerce and more.