I want to take a founder belief which will provide additional happiness. I'm unsure about the benefits of Ceremonial Burial vs. Peace Loving:
Ceremonial Burial
+1 Happiness for each city following this religion
Peace Loving
+1 Happiness for every 5 followers of this religion in non-enemy foreign cities
What are the precise benefits here, and under what conditions should I choose what? And is Peace Loving also applies for city-states, so I can rely on those as well?
The choice is based on how dominant you expect your civ and religion to be. Peace loving allows you to gain happiness from followers, even if you aren't the dominant religion in a city. Ceremonial burial requires that you be the dominant religion. Therefore, if you intend to put lots of effort into making your religion dominant by using inquisitors, GPs and missionaries, then use Ceremonial burial. If you are content to let your religion spread organically, use Peaceloving. Both do work on City-states. Additionally, CB gives a more immediate benefit, while peaceloving takes time to expand outside your borders. CB works on your own cities, while PL doesn't, so if you are dominating the game, choose CB.
In conclusion:
Dominant Civ and/or Religion: pick CB.
Lagging Civ and/or Religion: pick PL
Immediate need: pick CB.
