I would go for either IBM 483 (J2EE Technologies) or one of SCEA or SCWCD.
The WebSphere exams referenced (157/158) are application specific, and while they do stress some J2EE technology, they aren't definative proof that a certified person knows J2EE - they just know sufficient amounts in an exam about a proprietary tool to pass the
test.
483 is mostly on the technologies involved, and shows that you understand the concepts. SCWCD shows you understand to a great extent some of the specific technologies used for creating web-based applications. And while SCEA is time consuming (and expensive!), it's both impressive to many employers and valuable as a sign that you do truly understand architecture and J2EE in depth.
Just my $0.02, though.