You don't get to pick any park for EMH each day. There is a set schedule for it. So, depending on the day you pick will dictate which park will offer it.
Now, you can choose a certain day to stay at the resort to get the park you want for EMH.
It depends on what you have seen so far. If you've been to FOP, Na'vi, and ROL then I would pick HS.
If you haven't seen the offerings at AK yet then I would go with AK. Usually, the first six months of a new ride makes that park very busy even with EMH and HS will be a zoo for a while.
Also, this depends on who is going with you. If you have kids they may enjoy the New Toy Story Land more at HS than AK.
Again depending on the ages of your kids you may be better off doing MK for EMH.