This list always changes for me not just near a release, but about every year or so. Still, at the moment:
TWOK - Not only the most genuinely emotional of all the films, but one of the tightest scripts, thematically speaking.
Trek XI - Resurrected the dead, knocked the stodginess out of Trek, and remolded the world for the 21st century.
TUC - Just a grand adventure, and a great send off for the original crew. sort of tied up the "Cold War" allegory.
TMP - As long as I fast-forward through th eV'Ger cloud approach. It's more grand than boring, and it's a real SF plot.
TSFS - A decent follow up to Khan, with some budgetary and dialogue issues.
FC - The only time the TNG crew told a story, instead of sold a product. "And he piled upon the whale's white hump..."
TVH - Dated, sometimes corny, but still very funny. The cast were so comfortable in their roles here.
GEN - Unevenly paced and at times too navel gazing, hurt by the obvious absence of Spock and McCoy at the start.
NEM - Like watching a prize fighter walk out into the ring and do the same stupid crap, even though you told him not to. Slavishly copies the preceding films, like it was written by an intelligent but inexperienced thirteen year old.
INS - It actually makes me sad that this was the last thing Michael Piller wrote for Trek. A glorified TV episode.
TFF - Heavy handed, cheaply-made, and continuity hell. Although I do love the camping scene.
