This.

It is the best and more complete of AGEOD games up to now in my humble opinion. But it's also the most difficult
My second favorite is Wars in America, which is also somewhat less complex and time consuming. A great starting point to learn the AGEOD games system if you feel AACW daunting.
Napoleon's campaigns is a good game too, and if you are a Napoleonic enthusiast you will surely like it.
But its a step below AACW and WIA mainly because it lacks a long big campaign (it has a lots on medium sized scenarios and a very long but focused Peninsular Campaign) and because it's less polished than the other two.
Hope it helps!
Cheers