I've actively searched for years to find a system to dump my brain into and Notion is the absolutely perfect fit for me. The fact that everything is a page, anything can go into a page, and you can nest forever on the fly is exactly what I need to model my actual IRL problems.

Putting together a Christmas list? Create a list and start adding stuff. Ahh crap, I know I want a new TV but I don't know any specifics. So I just open up the TV item in the list and dive into my research. Create a database inside there for prospective options, a separate view for finalists. Copy in images, links to articles and reviews without "losing my place."

I don't have to spend any mental energy thinking about how to organize my notes because I can just pick a direction and go without being stopped by anything. Everything lives where it's most relevant I guess it how I'd say it.