First things first, I'm a pretty big James Bond fan, and this was very hard for me too choose.
1) I nearly went for Goldeneye as it is easily my favorite "current" Bond movie, easily Brosnan's best one. I love the story, I love the action, and the importance that it had in my life goes without words. But, it was a bit campy at times, sure a far-cry from the Moore days, but still not as "cool" as the originals.
2) I nearly went for Live and Let Die as well, as it is probably my favorite Moore movie. First things first, the theme song is easily my favorite of all the Bond movies... Maybe even my favorite McCartney song? Anyway, I love the boat-chase, the "Pimps" in NYC, and of course, Whisper. Okay, the ending sucks, but it is a "fun" movie, and I still love it.
3) Diamonds are Forever, Forever, Forever, Forever... The last Sean Connery movie, a sweet Mach 1 chase scene, and a rather odd story line. Not the best movie, but again, one of my favorites.
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So yes, I went with Goldfinger. Sure, it is a bit cliche (sp?) to pick it, but it is arguably the best as it pretty much sets the standards for all Bond movies to follow. Hot chicks, crazy bad guy with henchman, awesome cars, etc. Sean Connery was at his best in this one, no doubts there, and it continues to be my favorite Bond movie of all-time.