Understory + ACF. ACF Extentions for Understory. Provides custom fields and option pages support for Understory.
Understory ACF is licensed under the GPL v2 or later; Add Advanced Custom Fields support to Understory
Create resuable custom field group classes that contain all of your logic and keep your templates squeaky clean. Also easily create options pages. Field groups can be registered with post types, taxonomies, users, views or options pages.
See the wiki for more documentation.