Yes, Chezron, Stainless Steel is the safest and best wire to use, but very few can afford it. I did a lot of research and there are many rescues and others that use GAW. Yes it contains zinc, but as I found and many will tell you, unless your bird is going to live it in, (mine don't) and you have birds that will hang on it and chew it or climb it a lot, there is little worry. Because of that fact, (Zinc) I made certain to fill my aviary with perches, boings, atoms, and play stands. It is literally overflowing so they have no reason to need to climb onto the wire. And my birds are never left unattended or for any length of time as I work. When I am home, I open the window going into my aviary and they are free to fly in the house as they please.
As for the rust, mine is attached to my house and there is an overhang, so little water ges to it, and it will take years to rust.