Metal and quality — copper or stainless steel
Metal, and good quality with it
Metal and quality together sounds like a fairy tale. It is possible — and so, usually, is the price. Below roughly 1000–1500 zł you will not find anything properly made.
The condition is the material: it has to be copper or acid-resistant steel.
Copper is what whisky distilleries use, but it is awkward to weld and the raw material is expensive. I have personally never seen a copper set on sale for home use — the price would have to be astronomical. That leaves acid-resistant steel, and the figure above will cool a good many people down.
The main advantage stands: condensing efficiency far above glass, plus real resistance to knocks.