The format of you data is basically the method you are using to collocate it all in the same place. Excel, a .csv file, Atlas.Ti etc...
Selecting appropriate data (and project) storage depends on the project. Take into consideration the amount of data created - both in size and number of files; the level of security needed - does the project involve sensitive information, such as human related (PII, archaeological/anthropological, indigenous, or at risk communities), intellectual property related (created by the project, external, under a data-use agreement).
Backing up is a critical data consideration. Your data should be automatically backed up into three places and at lease one of them should be physical and one of them off-site (cloud). Back up into the most generic format you can that will easily get you back into your research (typically .csv, .txt, markdown)