Amazed no one has mentioned Emacs' org-mode yet. Nothing I've ever tried comes close to the flexibility and usefulness of org-mode in Emacs.
Combined w/ MobileOrg sync and the MobileOrg app, it serves all of my note-taking needs quite well.
It's much more than dumb text, too, like Evernote. Structured documents with headers, markdown-like formatting, links, fast-capture templates for stray thoughts, an Agenda system (if you want it, you don't need to use it, I do and have it sync w/ my Google Calendar), exportable to HTML and a few other formats (some people even maintain their websites using org-mode).
Keywords for marking entries and a good search system (combined with Helm it's pretty amazing).
Property drawers for entries.
It's a swiss army knife of productivity applications and I use it for note taking, documents, journaling (with automatic GPG encryption of the entry body), my agenda, quick-capture of ideas, tasks, etc... I use it for grocery lists even.
Org-mode really is vastly more functional than other solutions, with the added benefit that you can learn and use as much or as little as you want and not be bothered by what isn't useful.
The other thing I try to call out about org-mode is that there is nothing else that is likely to be around and useful in 20 years.
Right and the ability to customize every nuance of it w/ a tiny bit of Emacs Lisp (or not, that's not required) has been great.
For example I didn't quite like how org-drill, a spaced repetition extension for org-mode, handled flash-card grouping and drill selection at run-time so I completely customized it with my own group selection interface.
Far from as good and complete, and will never be as good and complete given the limitations of scripting vim.
Vim aficionados (like me) can use evil-mode in Emacs, to gain access to org-mode and keep the use of their existing editing knowledge.
What protocol does org-mode use for syncing with mobile devices, can it be adapted to use WebDAV?
An open ecosystem of human-signal-capture apps will improve security of the future, i.e. events that have not yet happened. The past is already well monitored and recorded. See "The Adjustment Bureau" for exploration of the topic.
If apps use a mature sync protocol (e.g. WebDAV, CalDAV), they can collectively debug interoperability and cross-platform issues related to that protocol, leaving them free to innovate on UX for mass or vertical audiences. Some examples:
MobileOrg (the extension to org-mode in Emacs) requires an index.org file that points at the org files you want to export. You configure it to dump out anything from that index to a specified directory.
You then use something to sync that file tree to any of your devices. I used BTSync for a bit but found it annoying and I now use Google Drive with a GDrive syncing client on my phone so that the mobile-org Android app is always up-to-date.
It's bi-directional and they use a checksum matching scheme and some import tooling that allows you to suck in changes to those index files from other clients.
I had mentioned that I do use orgmode, along with few others. But, my comment was further below yours, and was more of a "postscript". I definitely use it for most of my technical note taking, as it is part of my emacs workflow. For casual note taking I ended up using the other apps, to vary my workflow pattern and tool usage.
How is MobileOrg's search? I tried switching from Evernote on all my devices to synced text files, but I found that on my phone I really needed a text/file editor/browser that searched document contents rather than just title. Evernote does this, but I couldn't find anything else that came close.
I've been using the Orgzly (http://www.orgzly.com/) beta for a couple of weeks and quite liking it in comparison to MobileOrg. You may want to give it a try. I found it to be a bit easier to get started with.
Combined w/ MobileOrg sync and the MobileOrg app, it serves all of my note-taking needs quite well.
It's much more than dumb text, too, like Evernote. Structured documents with headers, markdown-like formatting, links, fast-capture templates for stray thoughts, an Agenda system (if you want it, you don't need to use it, I do and have it sync w/ my Google Calendar), exportable to HTML and a few other formats (some people even maintain their websites using org-mode).
Keywords for marking entries and a good search system (combined with Helm it's pretty amazing).
Property drawers for entries.
It's a swiss army knife of productivity applications and I use it for note taking, documents, journaling (with automatic GPG encryption of the entry body), my agenda, quick-capture of ideas, tasks, etc... I use it for grocery lists even.