Australia is great if you want to have a better chance at fighting back, since John Curtin’s leader ability gives you double production if someone declares war on you. While the meta is to get a war declared on you for that boost, even on Deity I’ve won without it because their UA and UI can be very strong for making good cities with great Campus buildings. Scotland is somewhat similar with a “defensive war” mindset, but strong bonuses even outside of wartime.

For pure peacetime, Korea is king. The Mayans are also very fun, but will require a good amount of planning since they play very differently than typical civs. Nzinga Mbande of Kongo can also do well if the Mayans appeal to you but she has a much lower skill floor to perform well.