I have used obsidian and excallidraw for my note taking, especially excallidraw for math where I draw with my tablet. But since I started using emacs for programing I would like to move to org roam for school notes. However, I have not found a good alternative program for obsidians excallidraw plugin (I find gimp a bit to big for my purposes).
I use Rnote to write freely on a big whiteboard and Xournal++ for taking notes over PDFs of lectures.
Rnote has a much more modern and user-friendly interface while Xournal++ has more features and has been around for longer. I use both where I feel each excels.