Avoid scouring as much as possible, but if you have to once in a while it's not the end of the world. This generally means never let anybody else use them, nor help clean up afterward. So, I keep some cast iron frying pans, but not a complete set of pots. Le Creuset is cast iron, with an enamel coated cooking surface. I don't have a lot of experience with it, but I've enjoyed using it from time to time at other people's houses.
Aluminum works great.
Handles metal utensils, and the occasional scouring. The latest I hear is that it does not cause Alzheimer's. Get the thickest you can because they will distribute the heat most evenly which means high temp cooking with less burning. One cheap place to buy them is a cookware outlet store in Kittery Maine. Or find a commercial cookware store.