Editor used in BlogEngine for editing post or page content can be easily replaced by another compatible editor. By default, BlogEngine uses Summernote, but it also comes with TinyMCE and Bootstrap.wysiwyg preinstalled. To switch, there is a key in web.config.
<add key="BlogEngine.DefaultEditor" value="~/editors/summernote/editor.cshtml" />This key is pointing to the page that is required and must exist in editor folder by convention. So for example changing key to "~/editors/bootstrap-wysiwyg/editor.cshtml" will load bootstrap.wysiwyg.
Making any JavaScript editor work with BlogEngine is very simple, here is tutorial on how to adopt popular CKEditor to work with BlogEngine.