I'm really surprised to read so much admiration for Dalton as Bond. His two films are at least in the bottom 50 percent of the collection, but quality of the films aside, he lacked the charm and sophistication of the Bond character, instead playing the role as an action star. If Bond is just another action hero, then he's quite wimpy compared to his muscle-bound box office peers. Brosnan was the opposite--very slick and a believeable lady's man, but after Goldeneye the level of writing really declined, and some of Brosnan's Bond films are ridiculous and barely watchable.
Roger Moore, the longest-serving Bond, understood the inherent camp and cliches of the role, and instead of trying to reinvent Bond as something he isn't (as Dalton did, in a predictable but regrettable reaction to the lousy tail-end of Moore's Bond career) played along with the joke. "The Spy Who Loved Me" remains one of the best Bond films (totally aside from the lovely Barba Bach's contributions) because Moore balanced out the illogic with his suave manner and great sense of humor. But Moore wasn't an action star, and never tried to be. By the time the series got to Octopussy and A View to a Kill, Bond films were more comedy than spy thriller.
Connery is the best Bond, easy, because even at his laziest (Diamonds Are Forever) he owned the role. His dry (and often dark) British humor has been imitated by the others Bonds, but never matched successfully, and he always balanced Bond's cold professional detachment with inner warmth and devotion to duty. The screenwriting on the early Bond films varied in quality, with some material (like the long underwater scenes in Thunderball) aging poorly, but Connery's take on Bond and nonplussed reaction to all manner of situations is timeless.