Rule number one: Don't use XML. Lots of folks make their code "simpler" by replacing two lines of java with 40 lines of XML. Some apps get to the point where the developer needs to know java plus 18 different XML schemas.
Rule number two: If rule number one won't work, use XStream if possible. Mixing Java and XML cannot possibly get simpler than this.
Rule number three: If rule number one won't work and rule number two won't work, use JDOM.