I've done a some investigation into this, and I can tell you while this looks cool. It'd be difficult to use on other devices (tablets, phones). The best I've seen is <a href="https://www.froala.com/wysiwyg-editor" rel="nofollow">https://www.froala.com/wysiwyg-editor</a>
Killer feature is the fact that I can use it on the iPad, Android tablet, IE, and Chrome. Also, its supports tables, which was one of the requirements for our clients.
Licensing is pretty affordable, and it's easy to integrate because there are plugins available for different frameworks (angular, django, ...)