Back in the days when I didn't know better and was trying to fit everything I had onto a 30gig HDD, I was using MP3 encoding with 160kbps sample rates, so a lot of my legacy stuff is encoded that way. Recently I started using the Apple Lossless format, which I find pretty good, so I am going to begin the arduous task of re-encoding a lot of my collection with this. However, I haven't tried any of the other options like AAC, AIFF and WAV, so I was wondering what the experts are using?