Sure, but for the sake of the exercise, let's assume that you can only pick one. Which would you think would yield better results?
In fact, even if we don't make this assumption, there really is one answer to which fix would yield better results. You may have a better shot at fixing one over the other as an individual acting individually. But then I have to question, is acting individually the ideal means by which you can employ to fix the issue? And as we're social creatures living in society, the answer to that particular question should be fairly obvious.
Now, I'm not factoring in your level of comfort, or whether you can make money doing it, or how many minutes of fame it'll get you, or any other such fringe benefit. Because as much as some of these people might be doing it for primarily those reasons, they're also genuinely trying to fix the problem or at least present solutions. And in this context, wouldn't you say there is one issue their collective efforts would be better expended upon addressing over the other?
Here's another way of looking at it. Going for the low hanging fruit is only effective if the immediate effect is necessary for survival or if the effort to get to the higher fruits are prohibitive. That is to say, you don't try to bail the water out first before you plug the hole unless you're sinking rapidly or there's no hole to be plugged and the water's seeping in through the cracks. This is because if you go after the low hanging fruit, you're not fixing the problem itself, just deferring the effects of the problem to another place or time. Are we in such dire straits, or the cost of the alternative so prohibitive that going after the low hanging fruit is necessary?
It's actually a trick question because both are low hanging fruit. Only, one is lower than the other. The fruit at the very top is impossible to get to without something drastic like say, cutting off all of the branches in between.