This is a difficult question without knowing which direction you'd like to take you career. SCBCD 5.0 is a relatively new technology / certification, correspondingly there are far more jobs out there requiring SCWCD like skills than there are
EJB 3.0. SCWCD is also a gentler introduction into the world of J2EE if that's what you're looking for.
At the end of the day, for pure bang for buck in the job market, I'd go with SCWCD first. That's not to say SCBCD does have value - even if you don't end up getting a job using EJB 3.0 it's a great introduction into the world of object/relational mapping with its coverage of JPA, and that is used (with products like Hibernate) pretty much everywhere.
SCJP, SCWCD, SCBCD, SCEA 5