There is no real right answer to this, but I reckon:

1. From Russia with Love - Bond's a hard ass, the bad guys a hard ass, he shoots a helicopter with a gun, there's a hot girl in it, there's a cracking train scene. Probably the pinnacle of the series.

2. Casino Royale - Reenergised a franchise that had died for me with TWINEnough. Borrowed heavily from Bourne and the original Bond's admittedly, but I loved every second of it.

3. Living Daylights - A bit controversial, but I loved it. Saw it at the cinema and I genuinely loved Dalton as Bond.

Honorable mentions:

Goldeneye - for introducing Judi Dench and giving us THAT game; You only live Twice - seriously, how can you argue with a film that has rockets firing out of volcanoes?; OHMSS - the most fleeting of Bond's also got one of the series' finest films; For your eyes only - the Casino Royale of the Moore era, often cruelly derided. Brilliantly tense and understated final half hour.

Worst?

1. Die Another day. Woeful. A part of me died watching it.
2. Never say never again. Not sure if officially this counts, but if it does then its crap.
3. Octopussy - Never liked it much, and Moore by this point looked near death.