Best spreadsheet editor (tie): Numbers
Apple's iWork Numbers spreadsheet editor is great at data entry, especially numeric, date, and formula info. The keyboard even adjusts based on the type of data you're working with. Cell formatting is less flexible than in Excel, and Excel users may dislike Numbers' approach to creating worksheets: Numbers allows several on a page. But the newest version better supports multisheet workbooks and adds CSV export, animated charts, and (unsecured) group editing via the Web.
Also, like all iWork apps, the only cloud storage service you can directly edit files in is Apple's own iCloud. But it does support AirPrint and PDF export.
(free on new devices)
Compatibility: iPad and iPhone