All WYSIWYG editors are a pain. They cause a lot of trouble. I have had instances where, under unexplained circumstances, the editor did not close tags correctly and ruined my whole layout.

I have recently discovered the Aloha Editor. Full HTML5 (or just HTML is you wanna be correct :P). Did not try it in production yet but it seems promising.

Check it out: http://www.aloha-editor.org/