WYSIWYG Email Editing?

How does the WYSIWYG editor compare to something like Mosaico ( https://mosaico.io/ )? The claim is that Mosiaco has special email compatibility support. Is that only due to their master email template; does Ghost have anything to rival the WYSIWYG editing capabilities of Mosaico? It doesn’t seem easy to integrate Mosaico with Ghost…

Thank you!