Evernote, being not Apple and the biggest name in synced notes, has a lot of integration features with other platforms that you’ll never get with Apple Notes.
The way I see it is this:
Evernote - strong integration with the internet
Apple Notes - strong integration with the system
If you are soundly tied into the Apple ecosystem and don’t see yourself ever moving. Use Apple Notes! If it works for you, is free, and well supported by the developer, there is no reason to look elsewhere.
If you frequently are using other devices like Windows machines and find yourself wishing you had access to your notes, then you shoud look at giving something like Evernote a shot.
Maybe you don’t have to use Evernote though, Dropbox Paper works very well for some use cases, Notion is very popular with its userbase, and Google Keep . . . exists.