Magellan Midstream Partners (NYSE: MMP) and Valero Energy (NYSE: VLO) both offer investors very similar current yields of 4.45% and 4.3%, respectively. Meanwhile, both companies have sector-leading credit metrics, which improves the security of those payouts. But while each appears to be an excellent candidate for an income investor's portfolio, Magellan has two additional security features that give it the upper hand for investors that value safety above all else.As a refiner, Valero turns oil into refined products such as gasoline and diesel.