There's a lot of hype about SOA, but perhaps less to it than meets the eye; that may still change though. In practice, any company that uses WS will also have web apps or EJB/DB apps, so either of those exams would help. There are certainly more companies that use servlets/JSPs than those that use
EJB, so I'd say the SCWCD is more useful than the SCBCD. Even better would be actual experience, of course.