DeNotes vs Evernote
Evernote is an archive. It is built to capture anything, from a web page to a scanned receipt, and find it again years later. DeNotes is built for writing, and keeps almost nothing you did not type.
What Evernote does well
Evernote has been doing this longer than almost anyone, and the parts it is known for are still good. The web clipper is the best in the category, search reaches inside PDFs and images, and it handles attachments, scanned documents and mixed media without complaint. If your notes are largely things you collected rather than things you wrote, that matters.
Where DeNotes is different
Evernote grew to cover a lot of ground, and the interface carries the weight of it. DeNotes is deliberately small: notes, files, folders, goals, and a Markdown editor with no toolbar. The storage model is different in a way that outlasts any feature comparison. Evernote holds rich-text notes in your Evernote account, and getting them out means an export in its own format. DeNotes writes plain Markdown into your Google Drive as you type, so leaving is not an operation you have to perform. What DeNotes does not do is clip web pages or search text inside images.
Should you use DeNotes or Evernote?
Choose Evernote
Choose Evernote if you clip a lot from the web, keep scanned documents and PDFs alongside your notes, and want search that reaches inside them.
Choose DeNotes
Choose DeNotes if most of what you keep is writing you did yourself, and you want it in a plain format in storage you own rather than in an archive you have to export from.