1Writer
Our sister site, The Sweet Setup picked 1Writer as the best note-taking app for iOS.
Plain text notes are a great way to future proof your documents, while remaining easily accessible on Mac and iOS alike. 1Writer was chosen because it easily syncs with iCloud/Dropbox, has support for multiple external services (CloudApp, Evernote, Droplr, etc), and includes powerful custom actions.
Read the entire review over at The Sweet Setup. You can purchase 1Writer on the App Store for $4.99.