Just use AIFF which is a Mac native uncompressed file. FLAC and ALAC (Apple lossless aufio codec) are both compression schemes. Hard drives are cheap. The only thing that might be better than AIFF is WAV. WAV does not support file tagging in a way that is acceptable to most people, even though it is documented by many to sound the better. If you so choose, you can convert from one to another. Nobody seems to really understand why (if at all) one could be different than another as they end up being the same bits. Ultimately the best thing to do is rip a few well recorded cuts and in the formats that interest you and see if you can discern a diff. I was amazed/chagrined. Later you can batch convert. What ever seems to be going on, it appears to be in "real time" playing, not the ripping. Once you get the rip correct conversions are easy, albeit painful to us OCD audiophiles.
The bit about SACD is really moot. One cannot directly compare as the SACD files are not compatible with most DACs.
The bit about SACD is really moot. One cannot directly compare as the SACD files are not compatible with most DACs.