Whopping 11 CDs with the whole OSTs from Breath of Fire 1-5.
As for the most music, I’d also say Smash Bros. Brawl. It, after all, has around 300 tracks.
Mother 3 does deserve a mention on the RPG section, though. Over 6 hours in a GBA game, that’s not for everyone!
Metal Gear Solid 4 is pretty big
Guitar Hero 3 is actually pretty long, when you get the DLC, but so is every music game now…
Brawl takes the Cake (Damn…)
Kingdom Hearts Complete Collection (9 discs of Win)
Animal Crossing on the Gamecube
Twilight Princess has alot
And the "Devil May Cry"’s 3 and 4
no contest
Brawl more likely though…