Good pans are worth their price because they manage heat better
"Good conductor" and "heavy gauge" are the key features of good cookware. Here's how these characteristics affect cooking.
You get responsive heat. Good heat conductors, such as copper and aluminum, are responsive to temperature changes. They'll do what the heat source tells them to do—heat up, cool down—almost instantly.
You get fast heat flow. Heat flows more easily through a good heat conductor, assuring a quick equalizing of temperature on the cooking surface.
You get even heat diffusion. A thicker pan has more distance between the cooking surface and the heat source. By the time the heat flows to the cooking surface, it will have spread out evenly, because heat diffuses as it flows.
You get more heat. Mass holds heat (heat is vibrating mass, so the more mass there is to vibrate, the more heat there will be). The more pan there is to heat, the more heat the pan can hold, so there's more constant heat for better browning, faster reducing, and hotter frying.
You'll want handles and a lid that are sturdy, heatproof, and secure. Handles come welded, riveted, or screwed. Some cooks advise against welded handles because they can break off. But Gayle Novacek, cookware buyer for Sur La Table, has seen few such cases. As long as handles are welded in several spots, they can be preferable to riveted ones because residue is apt to collect around a rivet.
Many pans have metal handles that stay relatively cool when the pan is on the stove because the handle is made of a metal that's a poor heat conductor and retainer, such as stainless steel. Plastic and wooden handles stay cool, too, but they're not ovenproof. Heat- or ovenproof handles mean that dishes started on the stovetop can be finished in the oven.
All lids should fit tightly to keep in moisture. The lid, too, should have a heatproof handle. Glass lids, which you'll find on certain brands, are usually ovensafe only up to 350°F.
A pan should feel comfortable. "When you're at the store, pantomime the way you'd use a pot or pan to find out if it's right for you," advises Fine Cooking contributing editor and chef Molly Stevens. If you find a pan you love but you aren't completely comfortable with the handle, you can buy a rubber gripper to slip over the handle. Just remember that grippers aren't ovenproof.
Some pans need special talents
Depending on what you'll be cooking in the pan, you may also need to look for other attributes.
For sautéing and other cooking that calls for quick temperature changes, a pan should be responsive. This means that the pan is doing what the heat source tells it to, and pronto. For example, if you sauté garlic just until fragrant and then turn down the flame, the pan should cool down quickly so the garlic doesn't burn. Responsiveness isn't as crucial for boiling, steaming, or the long, slow cooking that stocks and stews undergo.
For sautéing and oven roasts, it helps if the pan heats evenly up the sides. When you've got a pan full of chicken breasts nestling against the pan sides, you want them all to cook quickly and evenly, so heat coming from the sides of the pan is important. Even heat up the sides of a pot is important for pot roasting, too. Paul Bertolli, Fine Cooking contributing editor and chef of Oliveto restaurant in Oakland, California, counts on his enameled cast-iron oval casserole by Le Creuset for braising meat because "it's a snug, closed cooking chamber with even heat radiating off the sides for really good browning." Bertolli finds that meat fits especially well into the oval shape.
For cooking acidic foods, such as tomato sauces, wine sauces, and fruit fillings, a pan's lining should be nonreactive. Stainless steel, enamel, and anodized aluminum won't react no matter what they touch, while plain aluminum can discolor white sauces and foods that are acidic, sulfurous, or alkaline. It can even make those foods taste metallic. Eggs, vegetables in the cabbage family, and baking soda are some of the other foods vulnerable to aluminum's graying effect. In the past, there was concern about aluminum and Alzheimer's, but evidence has been far from conclusive.