For me, as a fan of the books & the films, the best Bond movies are the first three--Dr. No, From Russia With Love, & Goldfinger. Reason being, I feel that Bond truly belongs in the era he was written; he is a figure of the cold war. Though there have been plenty of successful modern interpretations, they're just that--interpretations. For me, Bond has the most integrity in his own time, where he's accented by the styles, the music, the misogyny, the women, & the life of an old-school spy.
That said, I enjoy the series as a whole & my second favorite Bond is Dalton, who might've had the top spot if only he'd had more time. Other stand-out films are The Living Daylights, Casino Royale, & License to Kill. Seeing Quantum in an hour, so can't report on that yet.