Put in anything you want. That state will never execute because you are telling the loop to stop because of the comparison at the bottom. Though I would probably pick either a default state that shows an error message since if it ever does run, you'll know something is wrong with your code because it shouldn't run.
Instead of comparing your shift register with a value at the bottom to determine when to stop, I would just put a boolean True constant in the Stop state and wire that directly to the stop condition terminal. Set the tunnel for Use default if unwired so that you don't have to bother wiring False constants in all the other states.
