I would recommend Noteshelf too as I feel like it's a lot more responsive than Samsung notes, especially with selections and drawing shapes. The only reason I can't use it as my main note-taking app is that there's no Windows app so I have to stick with Samsung Notes (which is almost as good).
If you can't decide between Notability and Goodnotes, go for Noteshelf.
It is by far better than these two IMO. It combines the neat features of both. For example, Notability's file management is utter shit and Goodnotes does it much better. Notability's text engine is also shit and Goodnotes approach is better but not as good as Noteshelf's.
Goodnotes has no ability to "save pens" so you have to change the pen type, size, and color every time you want to switch. In Noteshelf you can do that... or favorite up to 15 customized pens and change them on the fly activating the "favorites toolbar".
I know Noteshelf isn't as popular as the main two but after literal months of analyzing each app, Noteshelf is straight to the point without any quirks or limitations, fully customizable while having the cleanest and simplest UI.
Great. It might be good to clarify your post with that, because you'll see that a lot of the recommendations here are for what gives you the finest point. Which is more useful for handwriting than sketching charts.
Personally, for diagrams I used Noteshelf and Griffin's stylus. Both were OK, but I'm not sure they are what I would try again now that I've given up on the handwriting part. If I were to go back I might use something simpler for an app and something chunkier for a stylus, like Cosmonaut.