Basic Principles
FM is better
1. If Domestic Trade routes are worth more (your cities are large, you have overseas colonies, Harbors/Custom Houses are present, etc.)
2. If you have a large number of Trading partners (perticularly overseas ones)
3. If you have domestic corporations
4. If you have foreign corporations you want the effect of
Mercantilism is better if
0. You are running Representation (almost a requirement)
1. You have representation (obviously)
2. You are Isolated (all your Open border Friends are in Mercantilism)
3. You want to gain a competitive advantage, and are bigger than most of your trading Partners
4. You have Smaller cities
5. There are foreign cops that don't provide a good enough benefit, or at least they are funding a major rival
State Property is best when
0. you are running Caste System
1. You have very few Courthouses or Commerce/Science/Gold Multipliers in your cities
2. There are few useful corporations available... and a number of useless ones
3. You are in a hammer heavy strategy (typically military)
4. You have a very large empire
Environmentalism is best when
1. You are low on health (either from industrialization or running a Specialist Economy.. its worth ~2.7 specialists)
2. The UN forces you to