In AoC balance, Aztecs. They're so fun to play aggressively. Love the option for 5-unit drush/m@a, and IMO they have the among best options for forwarding in the game. In midgame, the eco bonus makes 1-TC aggression viable for longer before needing to decide between adding TCs or committing to a faster imp time or something. In lategame, there's nothing I love more than spamming champs with +8. Not necessarily the most viable strat depending on enemy civ, but beautiful nonetheless.

In WK though it's Slavs. Aztecs are still fun but the early 5-infantry-attack is a bit less viable with the tweak to their loom bonus. With the rise of eagles in Feudal and Castle, they're strong but I can't help but feel they play similar to Incas and lose part of what made them unique. They went from being a strong civ to a strong meso civ, if that makes sense.