TiddlyWiki! - One of the best and most underrated apps anywhere - seriously, check it out - I promise you'll be impressed even if it's not ultimately the best choice for you.
I'm in the process of migrating OneNote over to TW now. TiddlyWiki is extremely solid and stable, totally open (and hackable if you want to do that), capable of doing a surprising variety of things well (esp. with some plug-ins to add new capabilities), includes decent encryption, and stores your notes in a plain HTML file, though there are several ways to keep/sync TW to the cloud, too (requires a backend server or file sharing, obviously...) Being entirely JS/Browser based is the reason my 20-year-old TiddlyWikis still work as well today as when I created them.
The biggest advantage is that YOU are totally in control, with NO need to rely on any Evilcorp's support or services to access to your most important info.
I'm in the process of migrating OneNote over to TW now. TiddlyWiki is extremely solid and stable, totally open (and hackable if you want to do that), capable of doing a surprising variety of things well (esp. with some plug-ins to add new capabilities), includes decent encryption, and stores your notes in a plain HTML file, though there are several ways to keep/sync TW to the cloud, too (requires a backend server or file sharing, obviously...) Being entirely JS/Browser based is the reason my 20-year-old TiddlyWikis still work as well today as when I created them.
The biggest advantage is that YOU are totally in control, with NO need to rely on any Evilcorp's support or services to access to your most important info.