Best export format to work with problem audio

I am currently digitizing a batch of interview cassette tapes. Some of the interviews were on the phone, or a cordless phone or poor recording environs. When I first recorded the interviews, all I cared about was enough clarity to transcribe the interviews. Now, I want to use some of the interview footage for an audio documentary. That means cleaning up a lot of audio. I may need to share some audio files with audio engineers to see if some of these files can be brought into shape. What format would you suggest to 1) Work with audio files to reach a workable state 2) Share with others who are using proprietary DRM DAW’s.

24 bit wav is universally understood by DAWs.