I've finally decided to roll out version 1.0 of my XStandard module for Drupal.

So why choose XStandard over FCKeditor or TinyMCE? Simply put, it produces valid markup. The pro version can actually filter material pasted from Word into semantic XHTML while retaining structure. Here's a full feature list.

The blog Standards Schmandards has an excellent comparison of WYSIWYG editors.