One of the most maddening, frustrating parts of staying organised is that you can't just remember everything. We all keep notes in some form or fashion, and I've jumped from platform to platform, trying to find the best way to do things. I'll share what I know.
In order to be functional for me, there are several conditions that I look for. Having used a lot of notetaking applications and websites, the one thing that you should always be wary of before trying a new tool is how well it exports your content. Many note systems are very good, but they lock you into their app. Their business model is to keep you in a subscription, and to make it as hard as possible to leave. The more months you pay, the better.
To be effective, your ability to take or read something you've written has to be available when you need it. To that end, it's essential that your notes be available at home or at work, on your desk or your mobile.
What I mean by simple formatting is that it's readable. Too often, when you look at a note outside of a system, it loses all of its formatting. That is a non-starter.
For me, it's important to be able to keep certain text separate. In a very loose sense, we can call that "code". Maybe in other areas, it's just pre-formatted text, or text that you want to prohibit from being changed, etc.