What moral principle is best? Patriotism? Religion? Pacifism? Prosperity? Family?
No, it's environmentalism.
The human species is on track to be a horrendous flash in the pan, a creature that rapidly developed into the marvel of the animal kingdom and just as quickly ruined the world it inhabits.
Nation states compete, as do religions and businesses. Families look inward and multiply. Pacifists fruitlessly expect warriors to refrain from battle.
Environtmentalism works to protect the planet from the ravages of humanity. It's certainly not a perfect moral principle, because it has not embraced population reduction through the elimination of poverty -- despite the sure knowledge that overpopulation is an enormous driver of environmental waste.
It's frustrating to see, theoretically, that humans could turn planet Earth into a Utopia, with wealth for all and a sustainable ecology, while political, religious and business leaders are driven by a desire for power, instead of a deep respect for truth.
Scientists embody the virtue of gathering evidence and seeking the truth, and a vast majority of scientists support environmentalism.
Environmentalists, like other scientists, cooperate in their work, unlike the leaders of competitive organizations who drive us towards never-ending growth.
Think about it. Green supreme.