Notes should be easy to share (at least viewable, but ideally editable as well) by other people.
It should be highly enjoyable to write new notes and read existing notes. (iA Writer is the paragon here.)
Access to a mobile app.
Daily notes; as a corollary, how easy it is to just get thoughts flowing within the note-taking software.
How easy it is for me to link to things using Hook. (Is it zero friction?)
Is it 100% reliable? Am I likely to lose my notes, or for backlinks to suddenly stop working?
Is it easy for me to find things? Is it likely that I'll take some notes and they'll get lost in the shuffle of things, somewhere?
How well do backlinks work? Can I use them as a seamless way to view information about something?
Readwise integration -- can I use it as a central source of truth for all my thoughts?
How easy it is to export to different formats (formatted, HTML, Markdown). Also see: Notes should be exportable
Is it easy to send back and forth between formats, since I'm so fucking indecisive about which apps I want to use?
Table features
Extensibility (plugins) -- essentially speeding up the feature development process since we're no longer just dependent on the developers
Reasonable TODO management within the app.
Well thought out keyboard shortcuts.
Does it satisfy a niche that other apps don't provide? For example, Gingko feels just so natural and mentally smooth to use to organize information, and to go from outline -> draft -> final product. What are the unique pieces that each app gives me that I can't get from the other ones? What specifically am I missing out on?
Templates
Having a notion of a side panel, and being able to view multiple pieces of information side-by-side.
Once I've just added things to a page, brain-dump style (like I'm doing now), how easy is it to go through and clean up the page so that it conveys meaningful ideas?
Can I use the app to take long-form notes about articles and such? Is it easy to read and digest?