1. The Motion Picture - this is easy. The entire score is excellent, and quite distinctive from start to finish. It's also the best rendition of the ST theme as well. Standout tracks - all of them! But especially The Enterprise and The Meld.
2. The Final Frontier - as many have already said, it's a shame this wonderful score was wasted on such a terrible movie. You know it's a good soundtrack when you enjoy it without the connection of the movie, and TFF's score is no exception. It's also one of the few soundtracks where I actually enjoy the action-sequence music. This is a rarity for me. Standout tracks - The Mountain and A Busy Man.
3. First Contact - now, for the most part I am not a fan of the dark action sequences, but fortunately the rolling theme of FC is just so amazingly good, that I can just listen to it over and over. I would argue this is the BEST theme Goldsmith came up with in his career. Standout Tracks - First Contact
4. Star Trek 2009 - a real surprise! Of course, time will tell where I place this score, but for now, I really enjoy it. Initially I quite disliked it, but upon a second viewing of the film, I really got hooked on the theme. It's so impressive, and whilst lacking in a bit of diversity, it's still very good and is again, one of the few soundtracks where I can enjoy the action-music sequences on their own, not just in the film. Giacchino's rendition of the original ST theme is a bit hard to swallow though - reeks of Galaxy Quest/90's Lost in Space theme. Standout Tracks: Labor of Love, Enterprising Young Men and Star Trek.
5. The Search for Spock - The better of Horner's two efforts. It's a tad forgettable here and there, but for the most part it's beautifully constructed, and his Klingon theme is quite unique. Standout tracks - Stealing the Enterprise and Returning to Vulcan
6. The Wrath of Khan - Quite repetitive, but a good solid theme for Star Trek in the 80's. Standout tracks: Battle in the Mutara Nebula and Genesis Countdown.
Now from here, the rest of the soundtracks are mostly forgettable, so I can't really rank them. Not to say I dislike (mostly) them but more that I can't really enjoy them outside the movie.
Undiscovered Country is really good, but I can only enjoy it whilst watching the movie. Sign Off is the only standout track.
The Voyage Home suits the movie, but that's about it. I am not really a fan of this style of music, and there's nothing that really stands out for me.
Generations feels Next Gen, and most of the music in that was forgettable background music.
Insurrection suits the film, but is largely forgettable. Although I really love the 'New Sight' track.
Nemesis was entirely forgettable and probably the only soundtrack I dislike.