So, before making my previous post, I actually investigated GoN and StW, trying to see which can make the biggest cities, if that is our goal with the calabim (For feasting purposes)
Basically GoN works better with:
1) Few luxuries or other sources of happiness (Public baths, gambling houses)
2) Plenty of Trees.
Whereas StW works a lot better with:
1) Plenty of other sources of happiness.
2) Few or mediocre numbers of trees.
In case it wasn't obvious from my post, I do suggest getting FoL, to turn all your forests ancient, but they stay that way even after you abandon the religion.
Look at KingOfLands screenshot. A size 20 city, growing at a rate of +11 food per turn. Notice he has +20 more happiness than his population currently needs.
If you were to switch immediately to StW, health would decrease by 9 (Still in the positive) and you'd have two unhappy people since you'll lose that +22 national parks bonus (-4 food, we'll say). However, you'd be growing at + 11 + 20 (Half consumption) -4 (Unhappiness) = +27 food per turn... more than twice the speed of GoN.
If you weren't playing the Kurios, you wouldn't even have any more tiles to work, so additional population wouldn't net more food, so wouldn't help the city grow (Meaning the increased happiness wouldn't equal out to greater growth in the long run).
Anyhow, long story short, you will end up with bigger cities with StW, especially if you Anciented your forests, than you will with GoN, if you have high non-forest based happiness.