Finally, I found a suitable replacement for Onenote.
Originally when searching for my replacement I immediately looked into Evernote, yet it didn’t offer me anything differente compared to Onenote Online (via outlook.com). I wanted something local, with better response. Really I just needed a good way to organize my notes, I didn’t need anything fancy.
Here were my requirements:
Organize via tabs
Able to be backed up
I was able to save my CherryTree document into Dropbox, which made it “able to be backed up”.
I would suggest downloading the .deb or adding the PPA from guispen.com because the one that comes with Ubuntu (in the repo) is a few versions behind.