XML
Your first choice solution - Conventional word processing systems offer WYSIWYG, but they are not rule-based or in a translation-friendly form. Furthermore they are manufacturer specific and PDF/paper centered.
It is completely different with XML: On the one side you will find contents/structure and on the other side layout/description. You can save the contents independent of manufacturer or layout which will guarantee longlasting stability and flexibility. This is a definite advantage if publications are created in different media and output layouts.