Buy Amgen ( AMGN), Jim Cramer said Thursday on CNBC's Stop Trading! segment. Cramer said he'd like to know more about the big biotech's drug pipeline, and the fact that management has been mum on the subject makes him "nervous." Even so he believes the risk is 3 points down and the potential reward is 7 points up. Cramer said Amgen rival Celgene ( CELG) also presents an attractive risk-reward balance now. Cramer said he'd steer clear of J.P. Morgan ( JPM) because of big writedowns possibly just around the corner. Cramer would rather own Caterpillar ( CAT) even though the stock hasn't "acted as well" as rivals such as Deere ( DE).