@smalllife
Technically none. What they do have is a title (which you seem to scoff at, probably rightfully so). That being said as I am going through the CPA process right now, no Joe Blow can fake his way through the process. A CPA is truly one of the hardest working, most dedicated, and decent advocates you can have in personal finance.
That being said, growing up my dad did his own taxes, and I do my own. When a CPA gives you advice, it will have been researched and independent, they MUST disclose any association they have with advice given to you (commissions etc). A tax accountants goal is to get the most accurate return filed possible, they can't perform magic to inflate your refund, but with proper planning as mentioned in earlier posts they can certainly help plan for the best circumstance going into the following year.