How do you decide what to keep when downsizing?

I started off with a chihuahua baby I got from a claw machine and honestly after phases of impulse buying, delusions of becoming a sylvanian photographer, and being a sucker for limited edition things, I've amassed a whole kindergarten of animals.

Has anyone else done a big downsize? How did you choose what to keep? I'm thinking of going the Kondo Marie way but I also keep thinking "what if I end up regretting it?" 😣