Lower interest rates can help economic growth, but a recession would be bad for payment processors.Of the 30 components in the Dow Jones Industrial Average, Visa (V 0.94%) was my top pick for August. The stock had sold off due to a mediocre earnings report, but the long-term investment thesis was intact.Visa stock has continued languishing and remains a compelling buying opportunity. Here's why. The impact of lower interest ratesInvestors and economists expect the Federal Reserve to begin lowering interest ...