Which is best for Oracle DBA, connect to database in shared server mode or Dedicated server mode

Dedicated server mode.

These Actions required Dedicated server mode:
1- Recovery Manager (RMAN).
2-Operations that involve large data set:
- bulk loads
- data warehousing.
- DBA work

To bundle between the shared and dedicated server mode you can override shared server by defining alternate net service name, see below example.



NORMAL_USER=
(DESCRIPTION =
(
ADDRESS = (PROTOCOL = TCP)(HOST = myhost)(PORT = 1521)
)
(CONNECT_DATA =
(SERVER = SHARED) ======> look here
(SERVICE_NAME = emrepdb)
)
)

DBA_USER=
(DESCRIPTION =
(
ADDRESS = (PROTOCOL = TCP)(HOST = myhost)(PORT = 1521)
)
(CONNECT_DATA =
(SERVER = DEDICATED) ======> look here
(SERVICE_NAME = emrepdb)
)
)