Fall and winter apple varieties are in season from September through March, peaking in October. Fresh apples of any variety should be firm, crisp, and well colored, with no sign of decay, infestation, or dehydration. The flesh should not yield to gentle pressure.
Keep apples loosely covered at a cool room temperature. If your kitchen is on the warm side, however, it is better to store apples in a plastic bag in the refrigerator.
Golden Delicious are good all-purpose apples, and I use them when more interesting varieties are not available. Granny Smiths, also widely available, are tart and crisp, and sometimes remain too firm after being baked in a pie. They are better suited for cooked fillings, where you can cook them gently for a long time. McIntosh apples are best suited for making a sauce or purée, since they disintegrate completely when exposed to even the lowest heat. Northern Spies are the ultimate pie apple with a well-balanced flavor, juicy, but not watery flesh, and a slight firmness that keeps them from either disintegrating or remaining too hard. They are primarily available in the northern states from Minnesota eastward.