As a writer and iPad owner, I'm always looking for ways to use my iPad to write effectively. I do not need complex word processing software for my work - I just need simple plaintext editors that can sync with Dropbox, as I need a way to get my text on to an actual computer! Wordpress is still a pain to use effectively on mobile, though an app like Blogsy helps out tremendously. Here are my favorite 4 solutions for cloud-based text editing on iOS.
iA Writer: This text editor's greatest strength is its simplicity: pretty much the only setting that needs to be configured is Dropbox syncing, because it's the only setting. Files can be saved anywhere on Dropbox, and there's even iCloud support, which works with the Mac version of the software. The focus mode makes it much easier to just type without distraction, and the additional controls above the software keyboard make typing and editing text on the iPad screen far easier than any other app.
Notesy: This app's strengths are twofold: first, it features great automatic saving to Dropbox. While it only can sync up to one directory for saving files, it does have subdirectory support. The app also offers universal support, something that iA Writer lacks, which makes it easy for me to type up articles on my iPod touch when I'm not near my iPad, or in a situation where it's easier to use than the iPad.
Daedalus: What this app does differently is that it uses a stack-based interface, where text documents can be stored in logically-arranged groups of files. This works well for multitaskers who need to work on just specific sections of text at a time, like when composing lists, or for those who want some kind of visual arrangement of their work. Daedalus also has multiple display themes, customizable buttons above the keyboard, and multiple file export options.
Nocs: This app is designed for those who use Markdown; while it does type up plaintext and support editing of txt files in Dropbox, what this app brings to the table is the ability to convert Markdown to HTML easily. For those unaware of Markdown, it's essentially a variety of HTML formatting commands that are designed to be easier to type in than most HTML formatting is, and to look presentable when viewed as plaintext. Nocs can convert Markdown-formatted text into HTML files, suitable for pasting into Wordpress or anywhere else needed. Did I mention it's also free and universal?