In my corner of the world/philanthropy discussion, I'd consider GiveWell one of the most well-known organizations and with a reputation of high quality, thorough research. In terms of charity evaluators who focus on the impact per dollar spent, I'd have a hard time thinking of anyone comparable.

Regarding what type of programs GiveWell currently recommends, they do evaluate a wide range of types of programs. For instance, here is a page on their website summarizing some of their work on education: https://www.givewell.org/international/technical/programs/ed.... However, with the facts as they exist in the world today, their analysis is that for a given amount of funding, more good can be done with certain specific health interventions.

I think Givewell is excellent if your goal is to donate to charities that have been vetted for maximum impact (measured in terms of cost-effectiveness of dollars donated to saving lives) but if you are looking for a charity in a specific sector outside of one they have judged, they're not the best for that. But if you're a founder by chance, founderspledge.com supports people in figuring out where to donate based on their interests (and also publishes some of their research).

Give Well is a research organisation that publishes reports on the effectiveness of charities.

They do select a 'Top 9' of best charities for a range of issues, and also run a 'donation index' where you can allow your donation to be distributed to the top charities (purportedly without a fee being taken).

I've heard of Give Well being mentioned on various Stats podcasts (e.g. the BBC's More or Less) and Our World in Data is very reputable.