I have two Iron pieces from Le Creusete (or something)France, with glass enamel. Really heavy and life long guaranty, very expensive, but worth it in the long run.
(The saucepan was not available thats why I used the new one.) Bad choice.
What I do with the frying pan is that I spray some coconut oil in it when dry (wash it with water and sometimes a little borax); then polish it with a cloth. It looks great, no taste of metal or oil. No rust that I can see.
I find this matter difficult; not many good choices out there.