The most robust app is native to Mac. According to A Guide to the Best iPad Apps, Pages is the best productivity app for word processing.
The Pages app was specifically designed to work with the best iPad features. You can insert images into your documents and move them around by dragging the image with your fingertip. Pages makes formatting simple with built in templates and styles, as well as other common formatting tools.
Another key benefit to using Pages is the ability to save your document as a Pages document, a Microsoft Word document, and a PDF. You have the added benefit of being able to save the document to the iCloud and accessing from multiple devices.
Like Pages, Google Docs allows you to create new documents. However, Google Docs is not an app. It is accessed through iPad’s Safari browser; therefore, you must have access to the Internet.
When you initially create a new document or open an existing document, you have no formatting options. It is essentially just a text editor; however, once you start working in the document you can switch to ‘Desktop Mode’, which provides the standard Google Docs features.
Google Docs does have an app available for purchase through the App Store. The app, Go Docs, helps you organize and access all of your Google Docs in one location. If you download your documents to your iPad with this app, you will not have to on-line to access them.
Quickoffice Pro HD
Quickoffice Pro HD is another highly rated app available from the App Store. This app allows you to create and edit Microsoft Word documents, as well as PowerPoint Presentations and Excel Spreadsheets. Quickoffice ProD also provides you with a PDF Viewer.
Quickoffice Pro HD includes the ability to add list to Word Documents, view word counts and edit Word 2010 documents. It works with multiple versions of Microsoft Office, going back to Office 1997, as well as Google Docs.
Documents To Go
Documents To Go is another app with decent word processing reviews. Here is an app that give you access to your Word, PowerPoint, and Excel 2010 and 2007 files, as well as the ability to create new files from scratch. This app is one a few that also supports iWorks files, as well as GoDocs.
Documents To Go offers extensive formatting options, including bulleted lists, styles, Undo and Redo, find and replace, and word count. This app also uses InTact Technology to retain existing formatting.
Office2 HDhas the ability to create new Word documents, including Word 2010; however, it only goes up to PowerPoint 2003 and Excel 2007 files. Like Quickoffice Pro, you can also edit Google Docs.
This apps supports Undo and Redo, paragraph and character formatting, and images, as well as footnotes and endnotes. However, this app does not have an autosave feature. Users have commented that this has led to document loss. Also, there appears to be a formatting loss when opening a document with this app.
If you are looking for an app that simply lets you write text, then the iA Writer app is for you. This app has the highest reviewed keyboard that includes an extra row of special characters. iA Writer boasts a seamless sync between your Mac, iPad, and iPhone via the iCloud.This app is not an extension of Microsoft Office. It is a text editor that offers you simple word processing with a nice keyboard that gets out of your way and lets you simply write.