I see 4 key variables. They interact with map size, and also differ depending on whether you are playing humans or AIs.
In order of importance:
1. Gross wealth and shield capacity: Carthage, France
2. Early defensive advantage: Tricky: influenced both by traits and by S units. High scorers are the Militarists, esp. the Aztecs, but also the Ind. Trait. More important playing against Humans, who might be tempted to blitz you early.
3. Early productive bonus: Ind. Exp. Self explanatory.
4. Weakest factor, but not unimportant. Interaction benefits and losses. Rome loses out because war is bad for commerce. Germany can use sci trait to stay in the science race while fighting almost constantly and using garrsions to keep folks happy.
In order of importance:
1. Gross wealth and shield capacity: Carthage, France
2. Early defensive advantage: Tricky: influenced both by traits and by S units. High scorers are the Militarists, esp. the Aztecs, but also the Ind. Trait. More important playing against Humans, who might be tempted to blitz you early.
3. Early productive bonus: Ind. Exp. Self explanatory.
4. Weakest factor, but not unimportant. Interaction benefits and losses. Rome loses out because war is bad for commerce. Germany can use sci trait to stay in the science race while fighting almost constantly and using garrsions to keep folks happy.