Warren Buffett can hand-pick the CEOs of the companies Berkshire Hathaway (NYSE: BRK-A)(NYSE: BRK-B) owns outright, but that’s not the case with the stocks in Berkshire Hathaway’s portfolio. Since Buffett is a big believer that great management is key to long-term business success, let’s see how employees rate the CEOs of his five biggest stock positions on Glassdoor.