Nothing can compete with the Helms Deep scene, nothing. I can say that the matrix is a must see but there is nothing that can compete with the Lord of the Rings. It put a whole new spin of the genre and made everyone's life a lot better because of it.
Oh and, go Uruk-hai, the baddest in the land.
Although I love both the trilogies, nothing, I repeat NOTHING can compare to Tolkien. The years of work that went into his works, the depth of detail. I mean come on, he created whole different languages. The pure effort and hard work that went into his works just speak for themselves really.