MOV is Apple's homebody: gorgeous on a Mac, awkward everywhere else. It was born in 1991, Apple's QuickTime team, and its real weak spot is traveling: Windows, Android and the web would all rather meet an MP4.
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.