In principle, certifications don't teach - they are a proof of what you have learned already when you step into the certification process. In the end, it really doesn't matter whether you are learning the stuff on the way as long as you get to the finish line and pass it.

Traditionally IBM certifications have been more appreciated, I think, but nowadays IBM doesn't seem to have too many certifications for Java. Anyway, all certifications by the major vendors (Sun, IBM, Oracle, BEA) do have a certain industry value - when you apply for a position.