First Contact. It’s great.
Though I am a fan of all the stuff that involves the Borg. I also don’t mind Nemesis, it’s no masterpiece but it’s entertaining enough. Generations is decent but Insurrection is forgettable. Of the TOS ones, I haven’t seen them all, but Wrath of Khan obviously and The Undiscovered Country, which I saw for the first time only a couple weeks ago, was quite good. I thought Voyage Home and Search for Spock were also decent, but the Motion Picture is pretty boring. Haven’t seen Final Frontier.