After The Wrath of Khan (ST:II), this would have to be my next favorite. It is the first time in the movies that the core concepts that began Star Trek in the '60's were really addressed. It covered current social issues like racism (as mentioned earlier), and, to a greater extent, world change. This movie was made at the end of the cold war. Obviously that event was the basis for this movie. While Khan is still the best of the movies, it never dealt with anything more than revenge. There were no social implications considered. As with the original series (and Next Generation), this film took the issue of cold war hatred head on, and showed the dangers that were involved. This was Star Trek as it was first meant to be, and it showed that once again, people of all racial and political backgrounds can come to an agreement. That is what stuck me about this movie, and is why it will always be one of my favorites.