I can't speak for everyone else, but I think providing it in a format that's easy to work with such as an uncompressed dump (WAV?) would be the best.
WMA, for example, is actively protected by Microsoft who try to shut down any programs that allow you to open/convert them. FLAC can be a bit tricky for people to work with if they're not familiar with it. OGG will be compressed. Etc!
I could feasibly mirror it in smaller formats on grimfandango.net such as OGG and WMA once I've got the original rips.