If there's a dispute over a charge, I believe with debit cards the money is still out of your account until it gets sorted out -- this could be days or weeks.

With credit cards, the money in dispute is not "owed" to the card company, and at worst it reduces your available credit by that amount, which is only an issue if you're spending enough to max your card out anyway.

Even though the end result is similar, there's a bad feeling about the debit card fraud: It's my money tied up, while with credit it's the card issuer's money.