All of these are an issue of rates. And most of them have to do with deoxidation. This is a rate problem.
Right now the majority of plant life that is scrubbing CO2 is based in the ocean. in terms of land-based plant life that would help is likely the reversal of the desertification of certain areas like the Sahara. Which is also a large he at generator. In terms of Land Based efforts the most impact you can have on climate will be the reversal of desertification of that region.
Especially if we look at lessons from the US Dust Bowl to help solve that issue.
Tell me what's more likely? Reform of how we use CO2 as a global species or making efforts to increase the rate of oxygen producers?
if I were to bet Humanity on it I would definitely side with oxygen producers as being the most viable path unless you want to start some world wars to reduce the human population.