All those mentioned above a good, But..
There is a key decision to be made, do you want:
1) An app like Notes, Notability, etc. which store your notes within a database only readable by the app; or
2) An app which stores notes as files in a format which is portable to other apps?
In both case you can choose an app which synchronises (I don't call that backup) via iCloud, Dropbox or whatever.
If you choose (1) there are lots of apps, you need to try some. For typed notes, Bear is popular. But whatever you choose you are locked into the product and you will probably be unable to search the notes except within the chosen app.
If you choose (2), you are likely looking at an app which formats notes using the markdown format. This format is plain text with some formatting. It is indexed by Spotlight (as plain text) and searchable by Spotlight, Finder, Alfred, HoudahSpot, etc.
I followed path (2) when I stopped using Notes for anything but ephemera (e.g. shopping lists). Amongst markdown apps, I have been using Typora and One Markdown (there are lots of others). I store my markdown notes in a 2-level folder structure on my iCloud Drive. They are readable by Text Edit or any markdown app which will understand the formatting. I use Spotlight (or HoudahSpot) for searching.
And I backup my notes to a local drive and Time Machine.
Beside that:
Obsidian eats the lunch of whatever other program mentioned so far.
I found Obsidian (another markdown format app) too complex and intimidating for note taking. But it is very powerful and has a devoted following.