Stainless Cheese Graters are a no-brainer. Why on earth would you buy a Cheese grater that is going to rust? Stainless is the only way. No matter what type of Cheese grater you are buying, it should always be stainless.
There isn't really much to say on the topic, I actually don't know if you can even buy a non stainless cheese grater.
Cheese graters are an important part of the kitchen so always remember to buy a high quality one. Can I recommend a Drum Cheese Grater?