WMV is a time capsule from the Windows XP years: tidy little files with dated manners. It was born in 1999, Microsoft, and its real weak spot is everything Apple, most browsers, and any phone made this decade.
FLAC is the audiophile's handshake: CD-perfect sound at roughly half the shelf space. Free Lossless Audio Codec: think ZIP for sound: it decompresses back to the exact original. That makes it the right destination when what you need is archiving music with zero quality loss and a genuine size saving.