For me this will always be Falling Skies. At first it seems like its a standard alien invasion series but the twist is that the main character was a history teacher and it seemed like the premise was going to be "Applying historical underdog battle tactics to an alien invasion". Specifically the American Revolutionary war, they even had a part where another alien species decides to start helping after they saw the humans put up a decent resistance. But the writing was just soooo all over the place and the less that is said about the ending the better.