The Amazing Spider-Man 2 - My favorite by far. The best adaptation of Spidey as a character yet. Although I wish he had more screentime, I loved Dane Dehaan's take on Harry and the ending to the film was just amazing. I rarely get emotional during movies but this one had me. I thought they ended it on the best note possible too.
The Amazing Spider-Man - This is my close second. This is probably my favorite hero origin story put to film. The casting was brilliant all around imo, I don't think we could have gotten better choices than Garfield and Stone.
Spider-Man - Willem Dafoe's Green Goblin remains one of my favorite villains to this day. Although some disagree, I think this still holds up today (apart from some distracting CGI) and is still a great origin story. Awesome cast and even though I prefer the new series, I'll never get tired of this movie.
Spider-Man 2/Spider-Man 3 - Even though these are at the bottom, I still absolutely love both of them. My favorite stuff from #3 is all of the stuff with Harry Osborn but I don't have as big of problems with the rest of the film as most people do. Spider-Man 2 is great, I just don't love it as much as most people. Although he looked great, I just could never get super into the Doc Ock plot, just my opinion though.