Wither has more health than Ender Dragon and you cannot fight the Dragon in a specific place, it has to be in the End. On the other hand, nothing stops you from creating the Wither in a place where it cannot destroy your important buildings and items. read more
Enderman: Get angry when you look at them; Have 40 HP (20 hearts) Deal 7 Damage (3.5 hearts) Teleport; Cannot be shot with arrows; Iron golems: Get angry when you kill enough villagers/other iron golems; Have 100 HP (50 hearts) Deal 7–21 Damage (3.5–10.5 hearts, enough to one-hit kill you) Out of the two, I would say the strongest is the enderman. read more