Also none seem to be able to set up custom menus well if at all. Both WYSIWYG and custom menuing are must-haves.
My understanding is that you might be able to import your WordPress theme right into Windows Live Writer, thus replicating the visual aspects of your layout, but it's not for design purposes.
Custom menuing? Site development/design and writing content for your blog might be two very different things. I think generally speaking, desktop clients are for blogging, not for creating and applying design elements. The Visual and HTML editors in WordPress are for placing content on your site, not for site design. I'm getting the feeling that when you say "WYSIWYG" editor, you might be referring to website creation tools rather than content creation tools.