Here's a reminder of what's mentioned in game:
Syl'anar has the biggest military and economy. (That military mostly consists of war droids)
The whole world relies on Syl'anar's production of goods, especially electronics from Nero Inc, largely produced by elves.
Elves are not allowed to leave Syl'anar.
Syl'anar is very pro human immigration, and will incentivize that through discounts on elves, making Syl'anar the best place in the world to start a business.
Slavery is illegal everywhere else.