Androffice is in development. It only now supports XLS files.
Quickoffice is a paid program (normally $20, right now $10), but it does not support recent Word and Excel (2007) file formats.
DataViz's Documents to Go is $30, available through the Android Market (simple reinstall after device replacement or restore), and does far more than either of the others, or Google Docs for that matter.
It handles the 2007 Office formats, including PowerPoint that the others miss entirely (viewing is offered by Microsoft's Office Mobile) and adds PDF viewing as a bonus. It also supports more Excel functions than the others, and far more than even Microsoft's Pocket Excel.
Now, it's not perfect either. For instance, while it supports Office 2007 files, it only supports password-protected files through the 2003/2004 formats. But since Google has chosen not to include an Android-native version of Google Docs, this is the best option we seem to have at the moment. Check that - Documents to Go's "Sheet to Go" is better than Google Docs' spreadsheets - it supports more functions. Though of course, each is continuing to improve their products; if the simple number functions is a matter, either may pass the other at any time.
The "selling point" to me is that it can edit existing DOCX and XLSX files, without conversions, and without damaging any formatting/features that it doesn't support so they are still there when you open them back on a PC. That's what I got used to on a Windows Mobile phone; being able to do work from wherever I am, and in the same file formats. Even OpenOffice doesn't handle the DOC and XLS formats completely, so I need an app that doesn't damage what it doesn't understand.
Too bad none of these options have a Pocket Access equivalent. Microsoft dropped that from Office Mobile in 2000. I'd rather not need to buy yet something else, getting "nickeled-and-dimed", or more accurately $10 and $20'd, to death. I can manage one Office-equivalent purchase, justifying that the OS costs less than Windows Mobile. There are other benefits too, but that's another matter. I liked a lot of what WinMo included, and don't like losing them in order to get what it didn't include. Like a decent browser.