During my consulting engagements I see a lot of systems and many bugs. Most of the time, there is already a patch available to avoid the bug. I have collected all the recommended patches for the Oracle Database 220.127.116.11 (SE2 and EE) and Oracle Enterprise Manager 13cR2. This should help to avoid most critical known issues. Versions 18.104.22.168 and 18c will be added later this year.
Update: 18.05.2018: I have added a list of recommended patches for release 22.214.171.124.
Update: 17.07.2018: Updated EM 13.2 Patches