:O I was not in the wig/nemesis war, so I can't say for sure, but imo the most epic system war was zaft vs iG. That was sooooo intense, and it involved all the subclans too ^_^! iG just came up with some crazy good tactics that everyone uses today. (lol drop volley)
It is good to know that some other epic system wars have happened since then! I thought they all pretty much died out. **please devs work on pvp instead of pve!!!!!*