I recommend using Microsoft Excel ™ or Google Sheets ™ for financial modeling, both in general and for Foresight templates specifically.
In practice, I use Excel to build and edit models, and Google Sheets to share or collaborate with users. Excel is usually a faster platform for building models, but Sheets can be easier for sharing models with people.
Foresight's models can be used in both interchangeably; simply upload the Excel formated model template from Foresight into Google Sheets, and everything will work fine. 
Apple Numbers, Zoho Sheet, and Quip Spreadsheets aren't the best for robust financial modeling or for Foresight templates; I've used OpenOffice Calc without issues but would still recommend Excel or Google Sheets.
Some older versions of Foresight models will have issues in re-downloading models from Google Sheets into Excel because of the way the two spreadsheet products process array formulas differently, but newer versions eliminated the array formulas to simplify that process. ↩︎