Nickel silver wire will keep its color (no plating to flake off), and our nickel silver wire is more malleable than many on the market (it's close to feeling like sterling silver). It is a nice metal to work with, but you are correct - there are the allergy issues (and you can't sell nickel for jewelry in the EU at all).
Another option is
surgical steel wire. It's harder, so more difficult to hammer, but you have fewer allergy issues. Surgical Stainless Steel commonly has a small amount of nickel, but our 316L alloy has a very tiny amount. There is some more information about the various
Surgical Steels used in jewelry-making on wikipedia. 316L is a popular alloy for jewelry due to a number of qualities (workability, weight, durability, wearability) compared to other alloys.