This short white paper lists the major criteria:
When Should You Choose 12.1?
Consider targeting 12.1 if any of the following circumstances applies to your organization:
- You prefer to target a release on which Oracle has thousands of live customers.
- You would like to stay on 12.1 for 3-5 years before upgrading to 12.2.
- You need to move from a release below 11.5.10 with no direct upgrade to 12.2.
When Should You Choose 12.2?
Consider targeting 12.2 if any of the following circumstances applies to your organization:
- You need the high availability provided by Online Patching.
- You want the functional enhancements that are in 12.2.
- You prefer to invest in a single project to upgrade directly to 12.2.
It discusses those considerations in detail and provides links to other resources that you might use to weigh the pros and cons of each release.