White vs. Ivory Wedding Dress?

I've been doing some research online on wedding dresses, the thought never occurred to me that when it comes time to purchase a dress, I'll probably be given the option of white or ivory! What color wedding dress have you ladies purchased or are planning on purchasing, and why? Which color is the more flattering color? I've heard about stories of how the color white reflects 'purity' but do people actually still put that into consideration these days?