Evernote has a shite text editor that to this day has a lot of formatting bugs. BUt it's nearly ubiquitous, with support for it built into many other apps ("send to Evernote" and the like).

The Mac client, apart from text editing and a few niggles is also pretty decent in terms of layout, presentation and speed. It's much faster than many of the other similar apps I've tested over the past few years.

Its ubiquity is also a huge barrier to entry for competition. That part I don't like.

I keep a lot of stuff in Evernote, mostly put there from the Mac client, though it's also my go-to app when I need to document something on the road from my iPhone, usually by taking a photo and adding only a tiny bit of text.