Most people are selfish in their want to give. If someone close to me suffers from a specific form of cancer, I would be really motivated to give to that cause, in hopes that further research would lead to improvements in that area, and keep other people from going through the same suffering.
Therefore I'd argue, it would be WELL WORTH IT to curate a list of the most effective way to give towards research / relief regarding specific diseases. This would also motivate funding beyond what a single could ever contribute.
Sadly I am unable to find such a form of curation, most of the "giving effectively" foundations focus around a few select, broad topics. Would this be worthy of a project to pick up?
I agree - though not so much on everything gets funded anyway point.
I think there is also a wider meta question which is what is the best use of EA's marginal time/energy/money. My (highly unjustified) judgement would be that people donating for such causes aren't motivated by effectiveness, or at least are motivated much more by emotion. So the likelihood of changing their donation based on an argument around effectiveness may be quite hard to achieve.
I'm also not sure on the scale of difference between the worst and best charities for such causes (i.e. is the best cancer charity 100x better than the worst)? It'd be great to know, but assuming not, this would also reduce the benefit of any success.
A more effective solution achieve the same goal by proxy would seem to be just influencing the existing major funds or initiatives to focus more on the marginal impact of every £ they receive.