Meant for fun, not a balance discussion. Every civ has that other civ that they hate to be their neighbor, the one that is going to make this game just a bit harder for you than normal. Lets list out some of them.
Russia -> Shoshone: Nothing like getting forward settled by Shoshone and losing all of that land you had planned to turn into science. Further, while you could argue whether the Cossack or Comanche Rider is the better UU....the fact that both come out at the same time tends to limit your UU potential.
Byzantium -> Siam: Theodora has a truly great UU...often the linchpin of Byzanteen expansion in the medieval era. Except if your next to Siam....whose Elephant hard counters the cataphract. It doesn't hurt that Siam backed by some faith CS tends to pound missionaries like its going out of style.
Aztecs -> Greece: The Aztec jaguar rush can be very brutal...but finds its counter in the Hoplite. Further, Greece is often incentivized to get spears up early, so is normally ready by the time the jaguar rush finds them.
Austria <-> Germany: You can argue which one truly counters the other, but generally if both of these civs are near each other....it means war. Both have ways to secure votes, cutting off the others power. Austria has ways to hold CS allies away from Germany, while Germany's late game military can often crush an unprepared Austria.
Russia -> Shoshone: Nothing like getting forward settled by Shoshone and losing all of that land you had planned to turn into science. Further, while you could argue whether the Cossack or Comanche Rider is the better UU....the fact that both come out at the same time tends to limit your UU potential.
Byzantium -> Siam: Theodora has a truly great UU...often the linchpin of Byzanteen expansion in the medieval era. Except if your next to Siam....whose Elephant hard counters the cataphract. It doesn't hurt that Siam backed by some faith CS tends to pound missionaries like its going out of style.
Aztecs -> Greece: The Aztec jaguar rush can be very brutal...but finds its counter in the Hoplite. Further, Greece is often incentivized to get spears up early, so is normally ready by the time the jaguar rush finds them.
Austria <-> Germany: You can argue which one truly counters the other, but generally if both of these civs are near each other....it means war. Both have ways to secure votes, cutting off the others power. Austria has ways to hold CS allies away from Germany, while Germany's late game military can often crush an unprepared Austria.