Do ancient copper coins look better than ancient bronze coins?

It maybe because of the make up of bronze which is copper/zinc/tin. The amounts of each in ancient time varied. Another factor is just what type of soil the coins were buried in. Most Chinese cash coins are copper, though some are made of different types of copper. I have seen where they cleaned up easily and where they did not. Some having a very hard crust on them, from acid type soils. The same can be said of ancients & medieval coins from Japan or Vietnam. Some soils in Italy as well as Greece have high acid contents and that may be the more important factor not the metal the coins are made of.