Advantage of RMAN:
Incremental where only modified data blocks will be copied
Integrity check for the data block in case they are corrupted
Can do parallelism instead of sequential
It automatically manages the backup files without DBA intervention.
It automatically deletes unnecessary backup datafiles and archived redo log files both from disk and tape.
Only RMAN provides the ability to perform encrypted backups.
RMAN manages the delete archivelog policy.