The first 3 are, for me, equally great. TMP is a beautiful score that elevates the film tremendously. TOWK and TSFS are two sides of the same coin, hitting different buttons and making different points, but these feel like Star Trek scores. Horner matured a great deal in two years and his score for ST3 is more emotionally resonant and operatic. His Klingon theme rivals Goldsmith's and is almost never quoted in later productions. Yep there's a lot of Sergei Prokofiev in the music, but I love Russian classical music, so that's fine.
Horner went on record also saying that he wanted it, feeling it couldn't be Star Trek without the fanfare. Success has many parents.Interestingly, in Nick Meyer's memoir "The View from the Bridge," he says that the studio insisted that James Horner use the Alexander Courage TOS fanfare in his score. Meyer says he originally wasn't a fan of that decision, but that Horner found a way to make it work. Now, Meyer says it was "the studio" that wanted it, but the same studio people were there for TMP. So I wonder if it was actually Harve Bennett who wanted it, being that he was trying to be much more true to the feel of TOS with the second film.