Buy Costco ( COST), Jim Cramer said Wednesday on CNBC's Stop Trading! segment. Cramer said the warehouse retailer is uniquely attractive to shoppers because it's an ever-changing experience. "They have an exciting thing," he said. "They made it so you can't regard it as a Wal-Mart ( WMT) or a Target ( TGT)." (To watch Jim Cramer discuss the beauty of Costco with TheStreet.com TV's Farnoosh Torabi, click here .) Cramer likes Gap ( GPS) because of the incentives set up for new management. Cramer still likes refiners Valero ( VLO), Chevron ( CVX) and Conoco ( COP) despite recent warnings by Valero and Chevron, because he says recent weeks have seen refining margins "explode."