Small organizations are better

I would claim that there are enough philanthropists in the world, with enough money and interest to donate, that if there were clear and direct channels between them and those in most need, a significant change could happen.

The issue ends up being that the organizations that receive the money are usually the largest and those who can afford to have the PR machines that attract philanthropy. Unfortunately, these large organizations are also the ones which spend a lower percentage of the donation directly to the beneficiary. Instead they have many costs to cover (the salaries of the organization’s staff and the mechanisms through which the poor receive aid.)

So, stay local, go small. Try to find the grassroots organizations, or even better, groups that through endowments can cover all the administrative costs, and who can guarantee that 100% of your donation will go directly to those in need.