Apple lossless saves about 25%-30% of disk space and seems to be nearly identical but is limited to using iTunes.
This may be true for OSX, but not for Windows. JRiver Media Center 12 will playback AIFF, and Apple Lossless Files, as well as FLAC, WAV, Monkey's Audio and a a slew of others. Media Center 12 for Windows allows me to use something other than iTunes for playback, and at least in a Windows environment, I think Media Center sounds better than iTunes as well. I can be auditioned free of charge for 30 days. After that, it is $40, not a bad deal.
I know is the Apple forum, but there a lot of iTunes users that may find this information helpful.