Media Assistant - One of the best written plugins I've used in a long time...
With 500+ images in their photo gallery, a high end Landscape company I've been developing a site for needed something that added hierarchy and structure to their massive image library. Users needed to be able to quickly drill down to their particular interest, photos needed to be reusable, and trying to do this as a series of galleries manually wasn't practical, especially from a maintenance perspective. Shiny gallery plugins are a dime a dozen, ones that put images and media in context not so much.
Enter Media Gallery, simply put, this is the best plugin for properly tagging and managing images in Wordpress I've ever seen. You should make a donation to his charity if you use it, especially if you really leverage it. Hard to put a dollar figure on this, but easily $10k-20k if you hired someone. One of the best coding & programming jobs I've ever seen on a Wordpress plugin ever. Truly fills in a missing component.
https://wordpress.org/plugins/media-library-assistant/