Help me decide on a charity to put in my will

I've decided to leave half my money to charity. This will be in the form of real estate. How do I choose? Which criteria matter? These are my thoughts:
- should probably be local (I live in Luxembourg) as it will be easier for them to sell (or use) the property. Maybe still be worth the hassle to them intra-EU?
- makes most sense to leave it all to a single org for the same reason.
- a local branch of a large international charity sounds reasonable, but then we're limited to the usual suspects.
- OTOH, it would make a bigger difference to a smaller org (buuut would this achieve the biggest bang for the buck for the cause?)
- but bigger / more boring is also more "stable". I don't wanna have to change my will every few years if a charity folds.

If you have specific recommendations, I'm all ears! Causes I care about: environment/climate change, human / migrant rights, LGBTQ+ rights, women's rights / violence against women, antiracism, animal rights... I could go on. You get the idea.
What cause is most urgent/deserving/efficient? Climate change clearly most important... but I'm of the "it's kinda already too late / a lost cause" persuasion. Is that too defeatist?

Thank you!!!