I found this review of WYSIWYG editors interesting. It's a very specific review in that it rates them on the quality of the code they produce. JXHTMLEDIT did poorly, not because it didn't support the various types of code, but because it expected the user to understand and select the correct code themselves.
TinyMCE, which I think Janne has mentioned before in the context of Moodle integration, did quite well.