That's a tough one......
I bought the blu-ray 50th anniversary box set when it first came out and I'm still watching at least 2 (random from each era) Bond films a week....
The problem with this question is...many (almost all) of the Bond films are very watchable depending on my mood or what locations/Bond girls/villians I want to see.
I must admit, I don't watch the Craig Bonds over again...they aren't that fun for me and I can't wait until he gets replaced.
I love Pierce as Bond but I almost always grab a Roger Moore Bond flick.
I do love Sean as well...but Roger wins out.
Roger's Bond movies are so difficult to pick from because I love them all.
It would probably be - Man with the Golden Gun, Moonraker, Spy Who Loved Me (and i don't even like Barbara Bach) LOL
Fun Stuff:
Golden Gun - (many dislike this one but I don't) great locations (especially Scaramangas island), Herve is great, Christopher Lee is a great villian (the nipple is hilarious), I like Maud in this as well, It's also different watching Roger man handle Maud - this wasn't his usual Bond...he was a bit more gritty and tough (most of his other movies he would seduce the woman for info not man handle her).
Moonraker - Bond in space, Lois Chiles (I can't get over how much she reminds me of Milla Jovovich - she even has the same mannerisms), great special effects for the time, Drax is also a unique villian, the space station and the noah's ark reference, I didn't care too much for Jaws falling in love but I really like his character.
Spy Who Loved Me - I really liked Stromberg and the underwater city idea, the Egypt location is fun with the Jaws sequence, I like the soundtrack as well (bought that as an 8track tape when I was a kid), the underwater lotus was awesome and Caroline Munro (much better than Barbara Bach).