I think the highest MasterCard that NFCU offers in terms of benefits equivalent to the Visa Signature is the Platinum MasterCard. It adds the Extended Warranty Coverage and Purchase Assurance and Travel Assistance in addition to the MasterRental Insurance. But according to some people, the Platinum is a "basic" card, which I don't think is an accurate assessment of the card. I can kind of see where they're coming from since my CapitalOne Platinum has the same benefits, but that's kind of a different argument comparing it to another bank's product.
Really the biggest downside for the Platinum is that it has FTF fees, so it may not be the best card for traveling.
(Hover over pics for details) FICO: TU 731 (05/14/14) EX 749 (04/24/14) EQ 684 (02/05/14) Goal 700 FAKO: TU 761 (05/20/14) EX 761 (05/20/14) EQ 743 (05/20/14)