Research is difficult and results don't generalize that well. People are so different. Some can remember anything they read, while others don't remember even if they do take notes.

A better approach is also difficult, ie. asking yourself, do I need better note-taking and memorization of topics? Due to Dunner-Kruger effects, we rarely ponder this. Nowadays, a websearch is a very quick and accessible cop-out and, in many cases (not all), more effective.

Research typically show that pencil and paper works best for memorization. In my experience, I never refer to these notes later however. Wiki was a good idea in 1995, but taking notes shouldn't require arcane knowledge and have arbitrary implementation limits. Markdown is slightly better. As a tool, I prefer WYSIWYG into an accessible format.

For TODO-notes, a simple text-file serve me well. However, for note-taking that I want to refer to later, mindmaps works best digitally in my personal experience, both for memorization and reference.

A free version, though a bit limited, is FreeMind. Works well enough to navigate to find what you need, provided proper node names and structure.