Why not
SCJA?
It's cheaper than the others, only $100 USD, and it demonstrates a wider breath of knowledge than SCJP, as it requires knowledge of MIDlets,
Servlets,
EJB and JMS. Not overly in depth knowledge, so you don't have to read the entire JMS spec, but it does require a solid understanding.
The SCJA certification looks great alongside all of the other certifications. Plus, in a job interview you get to promote this as the 'latest and greatest' certification from Sun.
SCJA dude. That's what I say. But then again, I'm biased.