The supplemental benefits of CapitalOne cards are not as good as some other issuers.
Take CapitalOne Venture, their flag ship card, and say, Chase UA Mileage Plus Explorer as an example:
Purchase Protection (Max coverage)
CapitalOne Venture : $500 per claim
Chase United Mileage Explorer: $10,000 per claim
Auto Rental Coverage
CapitalOne Venture: Secondary
Chase UA MP Explorer : Primary
Travel Accident Insurance
CapitalOne Venture : $250,000
Chase MP Explorer : $500,000
The UA MP Explorer card also offers Return Protection, Price Protection, which the Venture does not.