This is not a competitive league table. All causes should be tackled simultaneously. What are you doing?

The key point in that article you linked to is:
"International demand has driven intensive agriculture, logging and ranching that has proved an inexorable force for deforestation; conservation has been no match for commerce."

It might not be clear enough yet for some people, but the underlying message of climate action like that happening this week is opposition to capitalist economic growth in general, since this is incompatible with survival of the environment. Airport expansion (which mainly benefits richer people who travel the most) is one example. Increasing destruction of habitat due to demand for land for animal farming, intensive crops and wood is another example. It's not either-or.

Commerce and the need for ever increasing profit in capitalist economies is the problem - a system that is destroying the environment and at the same time maintains such inequality that vast number of people continue to live in poverty (they need to consume more!) whilst others are able to consume many times the amount that is environmentally sustainable. A completely new way of living is necessary.