Hi Anindya and Paulina.
Well any choice is good. Both SCWCD and SCBCD are valuable certifications. If you have prior knowledge on EJB, then BCD will be easier may be, so it may be clever to take this one first as it may take less time and efforts. I don't think it's "Good" to take one before the other, so any order is good.
What I do think is both WCD and BCD give valuable knowledge and are, imo, complementary. Real world projects are made of plenty of technologies, sometimes even made of "home-made" technologies, copied on standards (like EJB), or common libs (like
struts Hibernate) and so on (you wouldn't believe things I saw...). So having a full, deep understandings on web & business components concepts is very usefull.
WCD gives you knowledge on webapp structure/Architecture (i'd say infrastructure) which is the basis of apps.
BCD gives you a business components architecture view, which is the next level. But BCD may be used with other things than webapps !
So, well, I don't know if my point is clear, I just think both of them are valuable, and no specific order is better than the other. I just think that, if you have the possibility to do so,
you should take both of them.