My uneducated opinion would be glass.. years ago we used to have this huge pyrex glass pot with lid, you could cook soup in it thats how big it was. Unfortunately it broke at some point. I'm not sure they still sell those things anymore, but I'd guess you can't get much better than glass! It was a colored glass, sort of like cranberry colored from what I remember. I guess it would be impossible to find a pots and pans set made from all glass though.. My 2nd guess would be enamel. Doesn't Le Creuset make this really nice enamel over cast iron cookware set (I also used to have one of these) - always wanted to get a bigger set, they are really nice (very hard to burn something in one of those) I'd guess the enamel would be much better than a metal as far as allergies goes, but that's just an uneducated opinion, I'm interesting in hearing what others say who have experience with allergies.
