I don't buy from the Delta site. But since retiring and upping my annual travel, I've been buying an annual policy from Allianz. And I charge most all travel to my Chase Saph Reserve.
The Allianz policy covers lots of things, the most important to me is medical evac coverage. I can handle the penalty on a trip cancellation (I've only cancelled 2 trips in my life, one medical and Delta waived the fee and the other for work and my boss covered the fee).
Because I do 10 to 12 trips a year, the annual policy is the best deal I've found.
And I use the Chase Saph Res card especially for car rental because it is primary (and the one time filed a claim, it was processed quickly with no hassle once the rental company provided me with the documentation required.