Connery contributed to Bond's status as a sex symbol.
Bond's suave style and the famously changing female leads of the films made the character a global sex symbol.
Computer analysis using the Golden Ratio of Beauty Phi determined that Sean Connery had the facial features most associated with attractiveness. Plastic surgeon Dr. Julian De Silva commented that Connery "has beautiful facial symmetry and gets closer than any other Bond to having what the Greeks considered the perfect face." 
Good looks are merely one component of the James Bond character. There are many other personality traits that make up Ian Fleming's character, and while Sean Connery may have the looks, he lacks in other areas. If we are going on pure looks alone, the study indicates Lazenby would appear above Daniel Criag, and few viewers would ever argue that Lazenby is a better James Bond than Daniel Craig.
[P1] Sean Connery has the physical features most associated with good looks. [P2] Other Bond actors do not possess these features to the same degree. [P3] Connery is the best Bond.
[Rejecting P3] Looks are not the only criteria for portraying James Bond.