You Only Live Twice because of the Japanese connection.
I don't care for Connery's Bond, so I'd take any Roger Moore film over any of these, but YOLT if I had to pick one. Dr. No and Goldfinger are classics though, as well.
And any "But Connery was the ORIGINAL Bond!" fanatics can put a lid on it, since Moore was originally cast to play the role before Connery was even in the picture....