To raise your credit score, focus first on revolving debt such as credit card balances or other lines of credit. Reducing the amount of debt you owe, compared to your available credit limits, will help increase your credit score. You don't get that same benefit with auto loans or mortgages, which have fixed pay-off periods.
While paying off the card with the highest interest rate first could save the most money in the long run, focus on cards with the highest balances if your credit score if your primary concern.