I tend to agree with General Dan, I like ACW: the Blue and the Gray because it focuses on the ACW. Playing in Europe or having war declared on me from a nation that was not involved in the real CW disrupts the mood for me (of course that's just my opinion, everyone has different preferences
). As General Dan mentioned, there are other mods that focus on European conflicts.
On the other hand, I do like how the ACW mod has the diplomacy aspect with other countries, as that was a very big part in the CW. For example, the South wanted to get trade agreements with England and France who needed cotton. The South also bought large orders of Enfield rifles from Britain before the U.S. could, which of course turned out to be one of the most common rifles used by the South
Anyway, just wanted to give my two cents!