Personally, i'd choose Coronado, but given the family factor AoA might indeed be the choice for you. It all depends on what you're looking for.
Is the Disney theming super important for your family? If so, yes AoA is the way to go. The Little Mermaid rooms are completely themed to the story, however, they do have the old room layout which can feel outdated and cramped. Coronado has its own unique beautiful theming, it just is not Disney specifically.
The rooms at Coronado for the most part been renovated and look more modern, spacious and sleek, which to me leads to a better experience. Plus, due to the tower, they have added many dining options. At AOA you have landscape and the Pop QS if you cross the bridge. While at Coronado you now have a quick service, a pool bar with food options, multiple sit down restaurants and a signature restaurant.
Both main pools are great for kids, the one at Coronado has a slide which is fun and the one at AoA has the cute nemo theme and plays music underwater which is neat.
For transportation AoA will have the Skyliner edge since it will have recently opened, which might make going to DHS or Epcot easier.