Take the later one. What happens if there's a mechanical problem on your AA plane, or a weather delay in Miami, or who knows what else, and your flight is delayed two hours? Then you have three hours to get off the plane, go through immigration/customs, travel from the middle of nowhere to downtown BA, go through security at AEP, and get to your gate. If there's bad traffic, or a big line at passport control, you're screwed.

Take the later flight from AEP. If everything goes smoothly, you'll have a few hours in the city to get a relaxing lunch and maybe do something fun. If things go wonky, then you'll at least have a time cushion so you don't miss the onward connection.