You just encountered the biggest downside of WAV - there is no "meta data" included in the files, i.e. no artist or song information. What does that mean for files stored on external hard drives:
- If you WAV on an external hard drive and you import these, none of the info will be displayed in iTunes (except for the filename). Of course you can reenter all that info into iTunes, but if for some reason you would like to use that hard drive on a different computer or system, or if you loose your library, all that info is gone.
- If you use apple lossless files, all the info is stored with the file, that is you import it into any itunes on any computer and all info will show.
Given that both are lossless, there really is no question which one I would use. And if you worried you can always convert the files (that you want to listen to) to WAV before a critical listening session.
AIFF does NOT have tags either, only Lossless, FLAC, AAC, MP3 do.