There of course are a million to choose from, but I just got done watching Jurassic Park for the 20th time, and the entire scene when seeing the Trex for the first time is unbelievable. It might be the most suspenseful and intense scene in movie history. All the characters act the way most humans would, the effects are revolutionary for the time (and better that most effects now), and there has never been a better monster reveal ever. Would love to hear more!