Temple of Artemis (2) (5 - 3) ToA is great, but it's not really the wonder one would hard build for domination.
Terracotta Army (18) (17+1) For domination, there's really only one wonder that's worth hard building, and it's the wonder that gives a level to each of one's military units. Not only are the benefits of this wonder best found when it's built and not when capturing it, but it scales with the number of military units one has, so it gets even more powerful depending on the sizes of one's military forces. There was really no other wonder that could win this specific category.
Tangent, but I think most wonders (maybe all?) should give a burst of culture or tourism when they're built. This would further incentivize players to actually build wonders, which would also be a benefit that lies outside of conquering cities for wonders.
Terracotta Army (18) (17+1) For domination, there's really only one wonder that's worth hard building, and it's the wonder that gives a level to each of one's military units. Not only are the benefits of this wonder best found when it's built and not when capturing it, but it scales with the number of military units one has, so it gets even more powerful depending on the sizes of one's military forces. There was really no other wonder that could win this specific category.
Tangent, but I think most wonders (maybe all?) should give a burst of culture or tourism when they're built. This would further incentivize players to actually build wonders, which would also be a benefit that lies outside of conquering cities for wonders.