Got to go with Battle Islands.... Skyrim is a good map but BI i find is really strategic, ebbs and flows in strengths are frequent. In other words fun!Castles i'm afraid would be my last choice. Theres only really one strategy and as someone has already said it often comes down to who gets first move at the center. Make those shortcuts worth 3 instead of -1 and it might become more open. The other 2 maps i've not played but look pretty good.