Population? Production? Science? Coal? Crabs maybe? No, sometimes most important thing in Civilization 5 is a time. You may think that your worst enemies right in front of you, but you never know what will come from the sea.
For AI I used Acken's Minimalistic Balance mod (https://forums.civfanatics.com/thread...) that looks pretty good and don't really affect on gameplay, but sadly cannot support more than 22 civs.
Music: Ross Bugden Rapture ( • ♩♫ Epic Music ♪♬ Rapture (Copyright... ), Evan King End This