Dalton's Bond created a believable character
Prior to Dalton's interpretation of Bond, the character was pure kitsch and lacked depth, humanity, and realism
Unlike other Bonds, Dalton’s portrayal of the spy eschews the cliché portrayal of the protagonist and the actor brings his own distinct flair and personality to the role.
Dalton’s Bond has an unmistakeable personality and presence that only Dalton offers. His Bond does not bust out cheesy jokes at every opportunity like Moore’s, he is more serious and establishes the image of Bond as a genuine professional looking to complete the assignment by any available means. Although he gives Bond his own unique flair, he doesn’t depart from the core themes present in any Bond character: a love for women, and a penchant for alcoholic beverages.
His two films were the most unmemorable in the series. They lacked iconography and failed to become cultural icons that many of the other films in the series did. Neither have a memorable villain. In The Living Daylights, the archetypal bad guy isn’t introduced until the film is half-way through and their plans for world domination are vague and ill-prepared, hardly giving Dalton’s Bond character a worthy nemesis. Similarly, the South American drug baron that constitutes the baddie in License to Kill is equally unmemorable. With such unmemorable films, and never having himself tested against a worthy opponent, it would be improper to crown Dalton as the best Bond of all.
[P1] An actor should bring something to a role nobody else can. [P2] Dalton brings something to the role nobody else does. [P3] Therefore, Dalton is the best Bond.
[Rejecting P3] The best Bond must have memorable films. Dalton does not. He is not the best Bond.