A long time ago I had a good look at WYSIWYG. I even built a rudimentary editor, that was in production for about a decade.
My conclusion was that WYSIWYG is pretty much guaranteed to be unreliable. My (long ago) review of every product I laid my hands on, confirmed that none of them could be trusted. (And because of the WYSIWYGness you simply can't easily see the unacceptable things they might do. I daresay the WYSIWYGness had encouraged the developers not to be thorough.)
My conclusion was, if it counts edit source (WYSIWYN).
I'd love to see something mentioned here that works, but I'm not holding my breath. (My observation is that the editors usually parse the source and work with DOM, not source. On the round trip source->DOM->source it's very hard to not have changes, unless you made that source in the first place).