glass

that is the best. you can find that visions cookware at garage sales and second hand shops. lack of availability is a good sign its healthy. teflon and other nonstick cookware is the worst. aluminum is second worse, especially the cheap stuff. the aircraft grade cast aluminum is not as bad, but who needs more aluminum? stainless steel is a compromise - nickel being the worst metal that may leach from it.

enamaled cookware is nice but is fragile and no good after any breach. never, ever use aluminum or teflon if you can help it.