WAV is uncompressed, same quality as the original CD.
WMA Lossless, is compressed, a bit more than 50%, so you can store twice as many in the same space, but, as it is lossless, the quality is strictly identical to WAV and the original CD. At any point in the future, you can convert it to any other format.
MP3, it is a lossy format. The difference might not be audible, but there is a difference.
WMA (Lossy) and AAC (Lossy) are lossy formats, used mainly by Windows Media Player for the first and iTunes for the second. AAC is an open standard. Both offer a better quality than MP3 for the same compression rate.
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If you convert to a lossless format, any lossless format, then you can always batch convert to any other format at a later time without any loss to the first compression.
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