The best addon for Firefox available!
If I were to chose only one addon to use in browser, it would be uMatrix: it almost replaces a lot of other privacy addons by allowing only desired requests (js, image-counters, facebook spyware buttons and etc).
This extension is incredible for advanced users, long live uMatrix!

A great addon, but I wish its functionality would be merged with uBlock Origin's functionality, because personally I want to reduce the amount of addons in my browser as much as possible.

better author, more control

omg, the ultimate manager!

better than adblockers for blocking domains, files by extension or type, and better than having hosts files in system, the only inability which can be compensated with ublock is blocking specific elements and hiding them without blocking whole website or all files, has so much abilities and easy to backup lists, one of my best extensions!!! also gives perfect picture of websites and elements on it, useful for winhttrack, also useful because can make files and localhost work offline by blocking 3rd party for file and localhost

Not much needs to be said other than this is an absolutely amazing addon.