I’d say, beside the classics that everyone already listed,
- Legend of Mana (SNES)
- EarthBound (SNES) and the fan translated Mother 3 (GBA)
- Mega Man X (SNES)
- Phantasy Star IV (Mega Drive / Genesis)
- Tales of Phantasia (PSX, not the GBA version)
But there’s so many to choose from, it’s enough for more than a life time :D
If possible, only convert the wav files to AAC and keep all lossy files as they are.