In light of the recent disaster in Sierra Leone and Hurricane Harvey and the resulting floods, while you have your choice of where to send relief donations, I recommend the United Methodist Committee on Relief. Of course, I am doing this because I am a United Methodist but also because 100% of the donations go to the relief operation (and not many other relief groups can say that). The overhead for the operation comes from other appropriations.
Also, it is better to go the donation route (whomever you choose) than donating materials and goods (unless requested). The people running the group have a better understanding of what is happening, what is needed, and how to get it.