I would rate First Contact as the 2nd best Star Trek movie, right behind The Wrath of Khan. Much like the Wrath of Khan, a Captain's old nemesis comes back to fight him in one last duel to the death. But for Picard, the Borg aren't just an adversary, they are his inner demons. It's clear that he'll do anything and everything to stop them from assimilating Earth, but he begins to develop a sort of Ahab Complex. For Picard, it is not just a duty to defend earth, it's an act of revenge. That's the strongest point in this movie for me: Picard's Ambition. However, the Data/Borg Queen "romance" could've been avoided. It would've been better to show just snippets of what is happening to Data, while focusing on Picard's mission to destroy the Borg. It also would've given more time to the secondary plot featuring Riker and Dr. Cochrane, which was more interesting than the Data Plot in my opinion.
Some might say that Star Trek 2009 deserves the #2 spot, but I think this film retains the cerebral elements of the Star Trek franchise, while bringing the action and tension expected of a big budget movie.