Thank you for contributing towards this! Some hopefully constructive criticism:

• The idea of comparing two charities together to see how different the good done by them is a good one.
• Your Comparison ... section seems a bit long and I think it could be condensed substantially. The description of MakeAWish seems a bit lengthy. The Nurse Family Partnership comparison doesn't seem that compelling. Your citation of a paper that there's a 1000:1 effectiveness difference between many charities is dramatic; put that near the beginning!
• I think you can move many sentences describing where your data came from to footnotes. Short articles are good! Wordy articles scare people away.
• I'd say that picking out a good charity is substantially more difficult than picking a good investment. In finance, there's good reason to believe that an arbitrary asset will not be a terrible investment (efficient markets) while in charity there is currently no corresponding reason to think that an arbitrary charity will not be terrible.