Spider-man 3 win this year.
There's a lot of mystery surrounding Pirates 3 (aside from the fans who know everything about it). As posters have mentioned, there hasn't even been a teaser/trailer for it yet.
I know Spider-man 3 has gotten a lot of exposure, but it's going to help. You have to remember that there's been around a 3-year gap bewteen Spidey 2 and 3. Sony is trying to keep Spidey in everyone's minds up until the release, and it's working. The film has so much buzz, and everyone's so excited to get a glimpse of Venom. I went to see 300 last night and when the new Spidey trailer started, there were a few "OH YEAH"s shouted out. But once the trailer was over, the whole audience of the sold-out showing was applauding and cheering.
Also, Spider-man 2 was a better sequel than Pirates 2 in many people's eyes. While Pirates has a ton of fans and the film was a smash hit, Spidey 2 was one of the best reviewed films of its year and was a step up from the original film of the series. Whereas as Pirates 2 received mediocre reviews (and some pretty bad ones), and I know that some people were turned off after seeing the film (like myself).
I just think that Spidey has the edge the year and I'm pulling for it to win.