Hi Mary and welcome to the forum. The question to also consider is what you would like your Air 2 to look like from the front. A space grey backing is the only one that will give you a black screen border. The others, silver or gold, are only available with a white front.I have a silver iPhone 6 and am about to purchase my iPad Air 2. I'm thinking of going with the space grey just so I have one of both devices.
What color option on the iPad has been best for you?