Highly recommend Workflowy (https://workflowy.com/). Its core idea is just recursive lists. Everything is a list, and every bullet can be expanded to become a top-level list. I've found this to be the most natural way for me to organize information, and there is a satisfying symmetry to it.
The developers are also clearly careful when adding new features, since they always compose well with existing functionality and create a multiplier effect on productivity.
I suspect the new features starting to come into Workflowy last year is due to Roam Research which came out about then, and has largely been at best a slight improvement over Workflowy.
I do use Roam personally, but they were very hamfisted with their monetisation effort early on, which left a bad taste in my my mouth. If I were starting today, I would use Workflowy and be paying them instead. From what I can see, it is the more carefully built product.
Mirroring + templates is a gamechanger. Being able to create boards is also really nice; whoever realized that lists are isomorphic to boards is a genius. You can switch between the two seamlessly without ever being afraid of losing information or causing unintended side effects!
Just waiting for it to support reminders, at which point I feel like I could use it for everything.
Been using it for about a decade too. Syntax highlighting, quick capture and mobile reminders are still on my wishlist, but so far it's still better than all other competitors for me.
The developers are also clearly careful when adding new features, since they always compose well with existing functionality and create a multiplier effect on productivity.