Great timing, we were just looking for a new editor for our project. Since there are so many choices, here's a list of everything mentioned in this post.

Trix - https://github.com/basecamp/trix - demo here: http://trix-editor.org/ by basecamp and used in v3, handles files/images well

Squire - https://github.com/neilj/Squire - used in FastMail webmail, better for text than images

ProseMirror - http://prosemirror.net/ - not great with images

Scribe - https://github.com/guardian/scribe - by the Guardian team

CKEditor - http://ckeditor.com/ - solid and very customizable, lots of plugins, a little dated in look/feel

Quill - http://quilljs.com/

Summernote - http://summernote.org/

wysihtml - http://wysihtml.com/

Etherpad - http://etherpad.org/ - collaborative realtime editing

TinyMCE - http://www.tinymce.com/ - older editor but still good

Textbox.IO - https://textbox.io/ - new from the owners of tinymce project

Froala - https://www.froala.com/wysiwyg-editor - solid editor, newer features like drag/drop images, v2 RC3 just released

Redactor - http://imperavi.com/redactor/ - we used this in production but quality has gone down, v2 is half the functionality at 3x the price, not recommended anymore