versatility, and iWork for balance of price and features.
WORKING ON MULTIPLE COMPUTERS
Google Docs is the only package that doesn't care what computer or mobile device you have, as long as you have a decent Internet connection.
Apple will have that, too, when an online version of iWork comes out. I have been trying out a beta of iWork for iCloud since early August and like how it's working so far. Although the beta lacks many of the features of the stand-alone iWork software, it has much of what I need.
Office's Web Apps software, meanwhile, is decent on its own, with more features than either Google Docs or iWork online. But it feels underwhelming compared with the robust, stand-alone offering I'm used it. That said, you won't need Web Apps if you have a Windows or Mac computer.
Office does get expensive if you want to use it on multiple computers. It's $280 for two computers and $420 for three. With multiple computers, the $100-a-year subscription starts working in your favour, though keep in mind you're paying that each and every year. Paying $280 just once for two computers is still cheaper than $300 over three years. The subscription extends to Mac computers, too. If you have only Macs, Microsoft has been offering a three-computer bundle for $150, though that's being phased out in favour of subscriptions.
The costs for Apple's programs also add up with multiple devices, but not as much. The license allows you to use apps on multiple computers, so you'll be paying $90 at most for Pages, Numbers and Keynote on regular computers and mobile devices. And that's $90 just once, not $100 a year. Apple hasn't announced pricing yet for the iCloud version, so stay tuned if you need to use it on Windows or Android devices.
When you use the programs with Microsoft's SkyDrive, Google's Drive and Apple's iCloud storage services, changes you make on one computer will appear on another. You no longer have to email files to yourself or carry USB drives, and you no longer have to worry about which copy is the latest.
I use Google Docs regularly for lightweight tasks, such as keeping my list of things to do. What I like most about Google Docs is the ability to have multiple copies open. If you make changes on two devices simultaneously, Google will figure it out and keep all copies synced within seconds.