I like stainless-steel/copperbottomed. You used to be able to get such pans with the copper actually as part of the pan, but now they only seem to come with a copper plate riveted to the bottom of a steel pan-shape. I had a set of such ( not at all cheap ) pans some years ago where the copper plates actually fell off the steel after very little use. I used to wonder what the hissing noise was while I was cooking. One day the hissing was followed by a loud crack, and the two pieces parted company. The manufacturers were splendid about it - they replaced the whole set, no question, no cost to me, with a more expensive set, which I am still using about 8 years later.