I've no problem with using LibreOffice for most of my document needs, but i haven't found a good substitute for microsoft's OneNote yet. I mainly use it to plan my RPG games and it helps a lot. What alternatives are there for organizing notes on linux, with similar features to those that OneNote provides?
There's a program called cherrytree that I think is very underrated. It's probably not a 1:1 replacement for OneNote but I recommend checking it out in case it fulfills a similar but different need.