Daedalus Touch
There is certainly no shortage of beautiful iOS text editors, but maybe you're like me and you have a problem. An addiction, really. This urge to try all the text editors, even though you've already found ten of them that suit your needs. Well, here's your chance to try another one! And then you should seriously seek help.
Daedalus Touch meets all the essential requirements, like iCloud/Dropbox sync, Markdown support, excellent export options, and TextExpander integration, but there are also a few features that set it apart from the pack. For example: rather than dealing with folders, you group text files into "stacks" that can be navigated via gestures. While editing text, you have access to a customizable toolbar above the keyboard, where frequently-accessed character keys live, including an awesome key to delete forward instead of backspacing.
As of this morning, Daedalus Touch has become even more useful because it syncs with the newly-released Ulysses III writing app for Mac OS X. If you'd like more information about that app, check out the freshly-minted reviews by Brett Terpstra and Ben Brooks.
The app is normally $5, but as of this writing (and for the next week) it's on sale for only 99ยข so get it while it's hot.