Apple Lossless, AIFF or WAV for itunes?


I have ripped my collection in itunes to AIFF but as I consider buying a NAS I here most are not compatible with AIFF files...is this true? Of the three which is best for sound quality and maintaining the correct metadata?
Thanks for your help!
theb2826
WAV. I have a WAV album downloaded from Juno that sounds much better than a FLAC rip through my Naim DAC. In fact, I'm astounded how much better it sounds. Only if WAV was more readily available to buy.
@Macdude

If you are comparing a download (WAV) with a CD rip (FLAC) you may well be comparing much more than the difference in audio codecs. They might be entirely different masterings or mixes. Unless you could be certain they are from identical sources you could not be sure.

You could rip your CD to WAV and then to FLAC and that would ascertain a valid comparison.
@Mwheelerk

I have compared flac vs wav rip of the same CD on my Naim dac and wav has more immediacy to it.

I was curious to how a purchased wav album sounds so different than my CD wav rip. Like you said, could it be a different mastering or conversion process to wav?