well egypt has the best priests but... The gold part is completely wrong. If I was just worried about gold they'd have the worst priests. Egyptians don't get coinage, thus they get 25% less gold out of a gold mine than choson or babylonian. Sure they bring in the gold faster but they also run out faster.
Now if you are converting non-catapult units on defense I think babylonian have the best priests, that 30 faster rejuvination is amazing. If you are converting catapults by far egyptians range is the best. If you are using them offensively choson is probably the best since they are cheap, note when offensively using priests you lose a lot of them to chariot archer raids, thus the savings is a huge difference.