The best credit card to book Delta flights in 2026 depends on whether you value "Brand Loyalty" or "Universal Flexibility." If you are a frequent Delta flyer, the American Express Delta SkyMiles® Reserve Card is the gold standard; it offers the highest earn rate on Delta purchases, complimentary Centurion and Sky Club lounge access, and an annual "Companion Certificate" that can easily offset the annual fee. It also provides a "Status Boost" to help you reach Medallion tiers faster. However, if you want the best overall value, the American Express Platinum Card® is often superior because it earns 5x points on flights booked directly with airlines (including Delta), and those Membership Rewards points can be transferred 1:1 to Delta SkyMiles. For those who want a lower annual fee, the American Express Gold Card offers 3x points on flights and is excellent for everyday "food and grocery" spending. Essentially, if you want the "perks" (upgrades and lounges), go with the Delta-branded cards; if you want the "points" (for the most free flights), go with the generic Amex Platinum or Gold.