I can't remember how well AIFFs support metadata. Probably better than WAV files; but I can't remember.
AFAIK, AIFF does indeed support metadata (which, I can't recall). But it's an older format, that's for sure.
I suppose you could use ALAC instead, but that's got it's own set of considerations.
The only *real* consideration here, IMO, is compression. AIFF, if I recall correctly, is uncompressed raw PCM whereas ALAC is still PCM but uses lossless data compression (at a varying degree depending on user preference, if I recall correctly). Ultimately, they're both lossless* (and there's no loss converting from one to the other or vice versa) so it really shouldn't matter. But all Apple devices along with MC supports ALAC just fine.
I'd personally recommend using ALAC over AIFF - there's no sonic difference between them, and you can even save a little bit of storage space by using ALAC (even though large TB drives are cheap these days).
*Actually, AIFF (along with WAV) would be considered pure, raw PCM and would not be considered "lossless" because there's no data compression being used, but I digress.