Ultimately it depends on what you want to use the audio files for. For collection purpose, you may want to have the files as close to original with complete information. Uncompressed format is your best choice. At times, though, you may want to bring the files on mobile where storage is more limited. You will need compressed files by then. I am not sensitive enough to notice the tiny differences between lossless and lossy formats, so technically I prefer files with small size so I can keep a lot of items before buying additional space.