As PP have said, whatever is perfect for YOUR feet. However ...
In terms of a CATEGORY of shoes, my answer is a water-accepting sports sandal; one with a backstrap that will stay on your feet on rides like Soarin', or on the hanging coasters at USIOA or Seaworld, should you go over there.
In my family, we like different brands. DH and DS17 prefer Teva Dozers, I like Clark Privo Sandals and Merrells, and DD7 is fine with her Land's End water sandals.
For winter travel, we all prefer Merrell Jungle Mocs, which are (obviously) not sandals, but repel water well and are very comfortable for extended walking.
One thing to note re: shoes for theme park walking: don't cheap out. Do you really want a pr. of $30 shoes to ruin your comfort on a $3000 vacation? Spend the extra to get a good shoe-- constant pain can really ruin an expensive vacation. Also, while you are at it, buy some Body Glide and apply it to your feet; it will prevent hot-spots that cause blisters. (If you spend extra for shoes that are comfortable, you'll end up wearing them a lot after you get home, even if they are a style you would not have previously thought to wear.)