I’ve chosen Elements as my regular note taker, and that shows in my descriptions. While I’m still not happy with its use of byte-order marks and CRLF line endings, overall it fits my way of working better than the others.
Before Elements came along, I got a lot of use out of Simplenote and have no regrets buying it. Apart from the lack of font choice, it has more features than the other apps, and I can see where one or more of those features—search, in particular—would make it the best choice for many people.
PlainText strikes me as better suited for long narrative files than short, list-like notes and probably a more comfortable fit on the iPad than the iPhone. It’s the best looking of these apps.
Nebulous Notes has lots of interesting features, but its user interface is just too flaky. And the semi-automatic syncing is a dealbreaker. I know some smart people who use it, but it’s just not right for me.
Screenshots of the winner, below: