Both programs focus more on cloud sync than the iWork suite does. Quickoffice can sync with GoogleDocs, Box.net, Dropbox, MobileMe iDisk and public iDisk, and Documents To Go adds SugarSync to that list. While Documents To Go works with a slightly broader range of online syncing services than Quickoffice, the latter app quickly makes up for this with the ability to drag and drop documents. Press and hold on the document, and you can drag it onto the linked service, then into any subfolder that you choose. It's far easier than Documents To Go's cumbersome system, which involves syncing with a desktop app that you need to install or doing a new "save as" every time you want to save a local file to an online service.
A recent update to Documents To Go got rid of a lot of the bugs that annoyed me when I reviewed the iPhone version in 2009. For the first time, typing did not lag as I wrote a script for a friend. The toolbar has been greatly simplified, with a lot of functions now appearing under pop-up menus. You get numerous document styling features that make the word processing functionality of the app feel a lot more like Microsoft Word. The update also fixed the bug that drove me to try Quickoffice in the first place, which was an error with Word 2007 documents downloaded from Google Docs. This was not an error on DataViz's end, but they were very slow to correct it after they became aware of it. Documents To Go still does not respect Google's hidden documents, which means you'll have a cluttered screen when logging into the service.
Quickoffice's interface has smooth popover windows and the ability to do multiple styling options to a document with ease. I love the ability to right or left justify with the swipe of a finger. When working on Excel documents, you can have tabbed sheets, which Documents To Go lacks. You can also create folders, which pretty much sold me on the software alone.
However, Quickoffice does have some big holes in it. It's missing some nice features that Documents To Go has, such as a full-featured spell check and word count. It has an auto-save feature that I've yet to figure out how to turn off and it'll often interrupt my typing to do an auto save for anywhere up to a minute or more, a pain when you're in the middle of writing and do not want to lose focus. There is no search option and it doesn't play very well with Apple's wireless keyboard. The full version of Documents To Go allows you to create and edit PowerPoint documents, but Quickoffice currently does not. This feature is slated to be added later this year.
Which to choose?
I'm going with Quickoffice. The ability to organize my documents into different folders, along with the drag-and-drop online sync make this the ideal program for me since I work on multiple non-related projects at the same time with very basic styling. Despite the quirks, ease of syncing is worth the frustration. I'm hoping that the next release will include a spell check and word count, because both are sorely needed. I also hope they do something about the pesky auto-save. Quickoffice is a separate $16.95 purchase from its iPhone app, but it's not a port and takes advantage of the iPad's features.
However, many folks may prefer Documents To Go. If you need to edit PowerPoint presentations or find that you can't live without a fully loaded feature set, it's a worthwhile purchase. The recent software update did a lot to increase the program's speed and compatibility with Google Docs. If you use SugarSync for your online cloud storage, it is your only option. A pared-down version of Documents 2 Go is $9.99, but spend the extra $7 and go for the full $16.99 version with cloud sync. Documents 2 Go is a universal app and can be loaded onto your iPhone.
Both Quickoffice and Documents 2 Go are excellent office suites for the iPad -- and are head and tails above iWork.