WriterPlus

I've been using WriterP(lus) for a few weeks to quickly capture notes. It's a fast and clean editor that even runs on old versions of Android. It doesn't support tags, audio recording, image attachments, in-note search, and there's no preview mode for a note. Even with all those limitations, it's great for a quick and dirty Markdown editor and it's staying in one of my  home screen folders unless and until I find a better one.