ContentSync for Sketch is deeply integrated into Sketch and includes many features:
Image syncing allows image layers and overrides to be dynamically changes per content version.
Set symbol instance overrides per content version. Create truly dynamic and powerful content structures.
Changing symbol instance types per content version. Create highly customizable designs per content version.
Sync more than just words. Synchronize text styles too!
Sync to multiple sheets within your spreadsheet.
Some details on how ContentSync for Sketch saves your settings.