I'd recommend Office 365 Home Premium. It includes 5 user accounts, each getting 1TB of OneDrive storage and access to the full MS Office Suite. The retail price is $99/year, but you can typically find discounts, e.g. here it's $70/year http://www.bhphotovideo.com/c/product/917386-REG/microsoft_6...

The native integration with Windows 8 is also quite nice. If you're not on Windows it still might be worth considering just based on price alone (especially if you use MS Office).