Extensive user of both, but primarily go with Evernote for the following reasons.
Evernote has more reliable and transparent sync. Apple Notes sometimes doesn’t sync and you have no idea of the reason, nor do you have any capability of forcing a sync.
Evernote can also handle large amount of data MUCH better than Apple Notes. I have 5000+ notes in Evernote, tried importing them to Apple Notes. Importation went well, but daily usage choked Apple Notes.
Evernote search is also much better than Apple Notes.
Evernote web clipper.
Reasons for using Apple Notes would be: (1) part of the Apple ecosystem and works well with other Apple apps, (2) free, (3) on iOS, very quick to just jot down a note from lock screen.
Evernote to me is much more a repository of information, while Apple Notes is more of a note taking app for temporary notes.