The value of a certification depends on the skills requirement for a particular job. If some one needs an EJB developer and you have SCDJWS, it is not very useful, similarly on a web services project, SCBCD is not very helpful. What do you see yourself doing in the next couple of years? Web services on J2EE platform or EJB development and pick your certification accordingly.
Another data point could be, are you planning to get SCEA in the future? If you are then I would go for SCBCD because as it stands now EJBs are used in SCEA (by the time you take it Sun may add web services too).
Another data point could be that the EJB specification is changing. EJB 3.0 spec will be finalized quite soon. While Sun may take some time to upgrade the exam, I would wait until the new version comes out becuase EJB 3.0 spec is quite different from earlier versions.
At the end, the short answer is "it depends." You are the best person to evaluate your circumstances and make a decision