3. Event Driven <-- This is consider experimental and should not be used. Improvements to Timer Driven over the years has negated the usefulness of this strategy and it has been abandoned. Only still exist to avoid breaking back wards compatibility for users who upgrade. It will eventually be deprecated and removed.
None of these option will provide you with the ability to integrate with a calendar for specifically executing on US holidays. That being said, everything you can do via the UI, you can also accomplish via external calls to the NiFi rest-api (this includes starting and stopping NiFi processors). So technically you could create you own external scheduler that makes calls to NiFi's rest-api to start specific processors and then again to turn them off later.