My favourite charities are the Cat's Protection because they helped me out a lot with Darcy, our stray who we recently rescued. The lady was just lovely and willing to give us advice and help us out with neutering etc.
Also the Cat Orphanage who are a local cat rescue charity where I live, we got Pepsi from one lady who unfortunately is retiring soon but there's a few others still working to rescue and rehome.
And NASSL, again a lady working on her farm relying on the public for donations, I have a soft spot for them as when I was in college we did bake sales for them and bought food and blankets and toys and the lady was always so grateful and lovely. When I had to rehome Tank for a girl at work again she was brilliant.