The difference between the Oracle and SAP Oracle agents is the way the backups are made.
The SAP Oracle agent is using the SAP Backup/Recovery tools (BRTools) for creating backups, while the Oracle agent is intereacting directly with the Oracle database.
If your DB Admins prefer to use the SAP BRTools like brbackup and brarchive for creating backups, you should use the SAP Oracle agent. If they are using just rman, you can use the plain Oracle agent.
Furthermore it also depends on how your Oracle database is licensed and who is providing support. If the Oracle databases are licensed through SAP and you get support from SAP for your Oracle database, it's better to choose for the SAP Oracle agent, because that's what SAP is supporting for backing up an Oracle database.
If the databases are licensed directly from Oracle, it's better to use the Oracle agent, because Oracle will most likely not support the use of BRTools for backing up the databases.