I agree with Knightowl.. Happy loss seems to have an instant effect, especially on larger cities. Poison seems to only give them diarreah for a week and eventually maybe one Pop. will die off.
Unhappy will take away specialists at times and often ends with starving a Pop anyways.
Of course it goes by the city for the most part. If I can investigate city, I will choose whichever vile act does most damage.
Seems to me that blowing the lighthouse up on a good coastal city could do just as bad as poisoning the water, so I like to investigate first, but If Im unable to, then I usually go with foment unhappy later in the game, after Hereditary rule is not so popular, and poison water in the early eras to stop their growth as best I can.
Edit- also if they turn their culture slider up to enable happy buildings, then it still takes from their budget and may even make them downslide science.
Forment unhappiness is useless in a globe theater city (I did my first mission in such a city, what a letdown that was).
The only case when Poison Water is more poweful than Foment Unhappiness is in the case a city wouldn't have any hit from an increased unhappy population while has already some troubles with unhealthiness.
the Solver Patch fixes this.poison water on marathon can destroy whole civs (at least until the patch),
24 poison for 24 turns, civ that had 7-8 cities with 15 pop can become civ that has 8 pop total (all cities on 1 pop) in just 50 turns (tiny on marathon), but on normal speed unhappines is better especialy if he is building spaceship parts or a wonder
I agree with Knightowl.. Happy loss seems to have an instant effect, especially on larger cities. Poison seems to only give them diarreah for a week and eventually maybe one Pop.
Has anyone had any luck combining building sabotage with poisoning/formenting? I'd imagine that taking out the granery (and maybe harbor, aquaduct, etc) would make poisoning that much more viscious. I've only tried it once, personally, and forgot to watch the effects.