Best airline credit card for flights (finance advise)

Looking for best credit card for flight discounts, milage and benefits?

Already have chase reserve, and amex platinum.
Looking to reduce flight cost for vacations, build up united bank or other methods to save and redeem flights for free.

Keep researching delta reserve, united infinite, american and alaska and all dont give a good discount. Mainly all are just used for free lounge access but not much on flight benefits.