BlueGriffon is a WYSIWYG content editor for the World Wide Web. Powered by Gecko, the rendering engine of Firefox, it can edit Web pages in conformance to Web Standards.
BlueGriffon complies with the W3Cs web standards. It can create and edit pages in accordance to HTML 4, XHTML 1.1, HTML 5 and XHTML 5. It supports CSS 2.1 and all parts of CSS 3 already implemented by Gecko. BlueGriffon also includes SVG-edit, an XUL-based editor for SVG that is originally distributed as an add-on to Firefox and was adapted to BlueGriffon.
I have tested most of the other HTML WYSIWYG apps. I prefer BlueGriffon. It doesnt add unnecessary code to your HTML. The HTML generated can be verified by validator.w3.org. I mostly write HTML with a text editor, but when I want WYSIWYG this is the one I use.