I can definitely vouch for cast iron. I've had a large pot and a large skillet for the better part of 10 years, use them all the time, and they are still in near-perfect condition. Copper does last, but cast iron actually gets better with age; after a few years of steady use, cast iron pots and pans will be so well-seasoned that nothing can stick to them.
Cast iron is:
- Dirt cheap;
- Long-lasting;
- Easy to clean (just rinse)
- Oven-safe (you can use it as a dutch oven, or for slow cooking).
As long as you don't mind the weight, and you don't let them rust (dry and lightly oil them after rinsing) you can't go wrong. I know some cooks that swear by their copper cookware, I know it has a lot of great properties, but considering the cost, I really think that cast iron is the best investment if you're looking to "upgrade" your cookware.
