Of the Targaryens who were still alive when Summerhall took place:
Mainline: King Aegon V, Duncan Targaryen (Disinherited), Prince Jaehaerys, Princess Shaera, Prince Aerys, Princess Rhaella, Rhaegar (Newborn), Lady Rhaella (Steffon Baratheons Mom),
Other Members: Vaella Targaryen (Daerons Daughter), Maegor Targaryen (Brightflame), Daella Targaryen (Eggs Older Sister), Rhae Targaryen (Eggs Younger Sister),
At The Wall: Maester Aemon
If no one were to die as a sacrifice in order for the eggs to hatch. Who would be most likely to get a newly hatched dragon?