Bear is clean and simple to use. Everything is tracked with hashtags, which makes it really easy to cross reference notes. I use it for my programming notes because the code snippet functionality is 💯. It also embeds links nicely and uses Markdown, so it's basically no-fuss formatting. You can save backups and import/export notes. IMO the only downfall is there's no other organization to your notes other than tags, so it can get kinda cray. Currently free, but costs money to get different app colors and sync with other devices.