Quill is a free, open source WYSIWYG editor that has just reached version 1.0, though it’s been public for two years. I was doing research recently and Quill was a top contender in the realm of open source editors.
What attracts me to Quill is it’s ease of use and it’s extensive API. It’s latest features of supporting more complex content like nested lists, videos, and LaTeX formulas are also welcoming.
But mostly, their standard editor, and the floating toolbar style offer two different, both very nice, editing experiences.