What is the optimal setting for importing CDs?

When you use iTunes to import a CD you have several options -- "AAC Encoder," "AIFF Encoder," etc. I'd like to have the best possible sound quality and avoid any sort of lossy compression. Which setting, if any, allows me to do that? I noticed the "Apple Lossless" option, but it sounds a little proprietary. I'm suspicious. So I guess my goal is the above, but using a cross-platform standard file format if possible.