mfc -
Certification Magazine www.certmag.com has some excellent certification assessment processes that you can use which provide impartial information, such as considering the certification name recognition; the size of the certified population; and the costs to obtain and maintain a particular certification and the resulting benefit to you from having gotten it.
The "gold-standard" audit leadership certifications included (obviously) the CPA; the CISA was second, with 11,900 people having sat for the exam last June; the CIA was third, having made a huge comeback after the passage of Sarbanes and in light of the whole focus on governance and internal control versus attestation.
The bad news is that the magazine notes that the pass rate for the CIA and CISA is below 50% for both, so being prepared is the way to go. Other certifications noted as strong for auditors were those that were fraud-related, information security, security and business resumption and continuity planning. Surprisingly, the IIA's CCSA (Certification in Control Self-Assessment) did not get a high mark, and it was viewed as more of a training certificate versus a certification. Other "certifications" not getting strong reviews from the magazine were those IT-related engineering-type certifications that were considered vendor related or vendor specific. Good luck with your preparations.