Unfortunately, the best one I've used as far as WYSIWYG is Dreamweaver, and I don't like it that much either, but it is a standard part of the toolset in many web shops, and you just get used to it.
I currently use Aptana for that sort of prototyping, which is not really WYSIWYG, but has a great preview function, and I don't end up having to go back through crappy WYSIWYG generated markup and cleaning it up later.
I have never used the php part of Aptana (don't do much php), but have friends who seem to like it. The JS stuff is brilliant, and the CSS editor pretty good too.