American Express' Optima True Grace Card and the Discover Card topped Agoura Hills-based J.D. Power & Associates' annual satisfaction survey. Cardholders listed customer service and low annual interest rates as most important in determining how much they liked their cards, according to J.D. Power's 1997 Comprehensive Cardholder Satisfaction Study of users of 54 credit cards. Aggressive solicitation programs from competitors mean that credit card companies need to enhance customer satisfaction and loyalty, J.D. Power said. The Discover Card topped satisfaction rankings for cardholders who don't carry monthly balances. The Optima True Grace Card led in satisfaction for cardholders who do carry such balances. The survey of 10,540 cardholders found the number of cards being used for purchases fell in the last three years, while the number of credit cards in the average consumer's wallet hadn't changed.