Not sure how anyone answers this without knowing which carrier better suits your routing, pricing, class of service, hard product, and soft product needs. What are those?

Mint may or may not be great, but it doesn't exist on most routes, while DL's F/D1 exists on pretty much all routes. Thus, maybe there is a comparison if you are a JFK-LAX flyer, but not on most routes. Same thing with lounge access, frequency, and price.

Without knowing your needs and preferences, all you get here is people telling you what they like about their particular circumstances which likely have none to do with yours, e.g., international.