best WYSIWYG editor from the UX side?
I personally use tinyMCE on my sites, it's not heavy, and you can use the IMCEbridge.

This module will install the WYSIWYG API, then follow these instructions for adding TinyMCE or any other you want.

The IMCE Bridge module can be found here and is compatible with CKEditor, FCKeditor and TinyMCE.