The problem with using a professional is that you have less information available for choosing professionals than you do for choosing stocks. If you pick one and he gets good returns, was it because of luck or skill? If he gets poor returns for the first 5 years, is it because he's investing in good values that are overlooked by the rest of the market (a long-term winning strategy) or because he's investing in the hot stock of the month that gets dumped soon after (a long-term losing strategy)? It's really hard to "verify" performance when that performance depends upon so many factors outside of the professional's control.
With individual stocks, companies are at least required to give a detailed report to the market every quarter. It's a lot of work to keep up on all the information that may be relevant to a company's performance (some would probably say it's impossible), but at least the information is out there. That's not the case when you're looking for information about a financial professional's performance.
If you really don't have time to spend on this yourself, I'd recommend passive investments. Index funds, treasuries, munis. When you buy an index fund, you're basically hiring the services of all financial professionals, everywhere, to do your research for you. And paying a significantly lower fee than if you'd actually hired one.