Definitely Raiders on top. It's classical even to today: Nazi badass, a not-so-godlike hero, a McGuffin that is tied with Bible (that's what make it quite mystery, right?), and introducing a new iconic hero that lasts forever.
Then... hmm, I wonder which one should I place at second, Last Crusade or Temple of Doom. Last Crusade is a great Indy (and movie) to watch, with witty script; humorous lines, father-and-son situations, Nazi bad-asses and especially, Sir Sean Connery. Yeah, Last Crusade is at the second place for me
But still, I still love Temple of Doom. This is the true B-movie style, with destructive cult, myths, Asia and such. I don't see why ToD isn't considered a great Indy movie.
But Indy 4 was a little bit disappointment to me. Isn't that a cliche for Indy movies that every temples that he entered will collapse?
. It's still a good movie, but comparing to three prequel, it is going a little backward.