If and when defensive stocks come back into favor, investors will need to make some decisions as to which companies in the Consumer Staples sector look most attractive.If size and market momentum were your only stock-picking criteria, then Walmart's (WMT 0.96%) $800+ billion market cap, nearly$700 billion in annual sales, and recent rally to an all-time high would be all you needed to know.Kraft Heinz (KHC +0.61%), on the other hand, is less than 4% the size of the retail giant -- by both sales and market ...