Correct me if I’m wrong here: The downside to the Allianz annual plan is that trip cancellation or interruption has a max annual limit, whereas per-trip plans cover each trip entirely.
So of you have to cancel a trip and use up your credit for the year, you are SOL for future cancellations, with an annual plan. Not great if you are taking expensive international trips, which are the only trips I insure.
Granted, cancellations may be rare, but that is why we are insuring in the first place...