Here’s what I would be looking for;

• Decent mobile app (more than happy to pay for this if it’s a one time fee)
• Bonus for a OneNote / Evernote style Android widget
• WYSIWYG editor on mobile and desktop (why in God’s name does every Foss notes app insist I use a markdown language?) with bullet points, numbered lists, bold, italic, underline, strikethrough, and headings.
• Checklists (as in, ability to add checkboxes to notes)
• Ability to create an arbitrarily deep folder structure
• Tags would be nice
• Import from popular apps like OneNote, Evernote, or Joplin is basically essential at this point. A lot of us have way too fucking many notes to move by hand.