lol, Britney has no classics. Her catalog is forgotten and is only remembered by those from the TRL era but isn't universally praised. It's outdated bubble-gum pop music.
Her past erratic behavior and infamous moments (i.e. attacking cars with umbrellas, shaving her hair off, losing custody of her kids along with her legal rights, etc) is what she's known for. She's more of a tabloid symbol than she is a musician.