I voted for AK based on it being my least favorite of all the parks(hard to sya that since we love all things Disney).
However, I believe Ak would be a very difficult park to close due to the animals. I would imagine closing a park (not that i ever believe it would happen) would be considered a temporary measure. It would be costly and a logistical nightmare to find new homes for all the animals. Then, once the park were to reopen, replacing all the animals would be equally challenging and costly.
MK and Epcot are untouchable so that would only leave DHS left to close. Problem there would be what Disney's contract with Pixar is and if there were any backlash from that.
My belief is that WDW would scale way back on other things before ever closing a park.
They could close resorts, waterparks, bus transportation, magical express, etc...lots of other areas to trim before admitting defeat and closing a park.
let's hope it NEVER comes to this.