I've said this before, and I'll say it again. Whatever shoe is comfortable for you that is already broken in. The worse thing you can do is buy a pair of shoes a week before your trip and expect them to have no problems. Odds are if you have some footwear choice that you wear on your day to day, it will be fine at WDW. I've done runner shoes, Birkenstocks, and most recently Vibram Fivefingers. I was used to wearing all of them beforehand, and had no problems wearing any of them. I do recommend sticking with a shoe that is versatile, something that can get wet if it rains or on Kali, and keep right on going. Having to sludge around all day in a wet sneaker is no fun at all.