That depends. Are you looking at preserving the music without loss of information? Then you need to use a lossless format like flac. Formats like aac, mp3, opus can throw away information you’re less likely to hear to achieve better compression ratios. Flac can’t, so it needs more storage space to preserve the exact waveform.
You can use a lossy format if you want. On most consumer level equipment, you probably won’t notice a difference. However, if you start to notice artifacting in songs, you’ll need to go back to the originals to re-rip and encode.
Embracer treats studios like they are disposable. They killed Volition (Saint’s Row), Free Radical (TimeSpltters) plus a bunch of other studios. All of that was because their $2 billion deal with the Saudi Government fell through. Some studios managed to escape when one of the Saber Interactive original owners bought back a bunch of studios. They recently killed Pieces Interactive (Alone in the Dark).
If a studio is owned by Embracer, they are lucky if they will be around in 5 years.