I personally would do MK, simply for the fact that there is more to do there so you should be able to get more accomplished. Which park is your priority, your favorite? Also there are a limited number of rides at the other two parks, make a list of what you would LIKE to accomplish at all three parks and see which is the longest or what has the more important things to you. Also, find a list of what is open in each park for morning EMH, because not everything is. I read a post the other day about a lady upset about what they couldn't do in MK during EMH morning. Some of the lands weren't open. I know ALOT about Disney but I did not know this simply because we don't do morning EMH, we do evening EMH.