DB cloning on daily basis I have a requirement from one of my teams which is database copy (cloning) from production to my test server on daily basis at a particular time. 

I know this is a very simple process which every DBA would perform. 

Should I use RMAN duplicate for cloning? Should I use Goldengate? Is there any way I can schedule the same without manual intervention?

Server - RHEL
Database - Oracle 12c/11g
This can be done in a few minutes with storage snapshots/cloning. If you can't do that, just go for RMAN duplicate. Both method can be scripted and scheduled to run automatically.