We have traveled both ways. The plane is faster. You can get it at the same airport you land in. The airport is small and the planes are the ones with just a few seats. The view from the air was great of the islands and beautiful water. It only takes about 15 minutes. The ferry boat is cheaper and takes longer. If the weather is nice and you like an hour or so boat ride it's great.
Either way you are there and the last stretch to AC is short. Have Fun.