Mine changes depending on the day of the week or what mood I'm in, right now I'm trying to get friends into some DC stuff. I always use Morrison and Porter's first JLA arc, since it's easy to get into, all familiar heroes, and cheap if they want to buy it. Unless they want the hardcover. That raises the price somewhat.
I'm also handing out the New Frontier quite a bit, as it's a nice history lesson through the DCU, and give nice little moments to everyone, with a focus on Lantern, Flash, and J'onn.